diff --git a/app/decoder/ffmpeg/ffmpegdecoder.cpp b/app/decoder/ffmpeg/ffmpegdecoder.cpp
index 5f448295d..e3f6e3368 100644
--- a/app/decoder/ffmpeg/ffmpegdecoder.cpp
+++ b/app/decoder/ffmpeg/ffmpegdecoder.cpp
@@ -218,8 +218,8 @@ FramePtr FFmpegDecoder::Retrieve(const rational &timecode, const rational &lengt
     if (got_frame && (frame_->pts > target_ts || frame_->pts == AV_NOPTS_VALUE)) {
       // If we already tried seeking to 0 though, there's nothing we can do so we error here
       if (last_backtrack) {
-        Error(tr("FFmpeg failed to seek to the correct location"));
-        return nullptr;
+        // Must be the earliest frame in the file
+        break;
       }
 
       // We can't seek earlier than 0, so if this is a 0-seek, don't try any more times after this attempt
@@ -597,6 +597,14 @@ int64_t FFmpegDecoder::GetClosestTimestampInIndex(const int64_t &ts)
     Index();
   }
 
+  if (frame_index_.isEmpty()) {
+    return -1;
+  }
+
+  if (ts <= 0) {
+    return 0;
+  }
+
   // Use index to find closest frame in file
   for (int i=1;i<frame_index_.size();i++) {
     if (frame_index_.at(i) == ts) {
@@ -606,5 +614,5 @@ int64_t FFmpegDecoder::GetClosestTimestampInIndex(const int64_t &ts)
     }
   }
 
-  return -1;
+  return frame_index_.last();
 }
diff --git a/app/node/block/block.cpp b/app/node/block/block.cpp
index d3c24961e..5e5ed1156 100644
--- a/app/node/block/block.cpp
+++ b/app/node/block/block.cpp
@@ -127,6 +127,8 @@ void Block::Refresh()
   // Update out point by adding this clip's length to the just calculated in point
   out_point_ = in_point_ + length();
 
+  InvalidateCache(nullptr, in_point_, out_point_);
+
   emit Refreshed();
 }
 
diff --git a/app/node/block/clip/clip.cpp b/app/node/block/clip/clip.cpp
index ae44cdc51..6ffd423d2 100644
--- a/app/node/block/clip/clip.cpp
+++ b/app/node/block/clip/clip.cpp
@@ -103,3 +103,14 @@ void ClipBlock::InvalidateCache(NodeInput *from, const rational &start_range, co
     Node::InvalidateCache(from, start_range, end_range);
   }
 }
+
+QList<NodeDependency> ClipBlock::RunDependencies(NodeOutput *output, const rational &time)
+{
+  QList<NodeDependency> deps;
+
+  if (output == texture_output() && texture_input_->IsConnected()) {
+    deps.append(NodeDependency(texture_input_->get_connected_output(), SequenceToMediaTime(time)));
+  }
+
+  return deps;
+}
diff --git a/app/node/block/clip/clip.h b/app/node/block/clip/clip.h
index f611c1f6c..ae5005216 100644
--- a/app/node/block/clip/clip.h
+++ b/app/node/block/clip/clip.h
@@ -44,6 +44,8 @@ public:
 
   virtual void InvalidateCache(NodeInput *from, const rational &start_range, const rational &end_range) override;
 
+  virtual QList<NodeDependency> RunDependencies(NodeOutput *output, const rational &time) override;
+
 protected:
   virtual QVariant Value(NodeOutput* output, const rational& time) override;
 
diff --git a/app/node/input/media/media.cpp b/app/node/input/media/media.cpp
index 75873f12b..309e1c15d 100644
--- a/app/node/input/media/media.cpp
+++ b/app/node/input/media/media.cpp
@@ -97,12 +97,13 @@ void MediaInput::SetFootage(Footage *f)
   footage_input_->set_value(PtrToValue(f));
 }
 
-void MediaInput::Hash(QCryptographicHash *hash, const rational &time)
+void MediaInput::Hash(QCryptographicHash *hash, NodeOutput *from, const rational &time)
 {
-  Node::Hash(hash, time);
+  Node::Hash(hash, from, time);
 
   // Use frame value from Decoder
-  if (SetupDecoder()) {
+  if (from == texture_output_ && SetupDecoder()) {
+    qDebug() << "[MediaInput] Hashing pts" << decoder_->GetTimestampFromTime(time);
     hash->addData(QString::number(decoder_->GetTimestampFromTime(time)).toUtf8());
     // FIXME: Add OCIO data
     // FIXME: Add alpha association value
diff --git a/app/node/input/media/media.h b/app/node/input/media/media.h
index f0278a2f0..e0240130b 100644
--- a/app/node/input/media/media.h
+++ b/app/node/input/media/media.h
@@ -51,7 +51,7 @@ public:
 
   void SetFootage(Footage* f);
 
-  virtual void Hash(QCryptographicHash *hash, const rational &time) override;
+  virtual void Hash(QCryptographicHash *hash, NodeOutput* from, const rational &time) override;
 
 
 
diff --git a/app/node/node.cpp b/app/node/node.cpp
index 8107c6302..ae987e1ae 100644
--- a/app/node/node.cpp
+++ b/app/node/node.cpp
@@ -77,7 +77,9 @@ void Node::InvalidateCache(NodeInput* from, const rational &start_range, const r
     // If the Node is an output, relay the signal to any Nodes that are connected to it
     if (param->type() == NodeParam::kOutput) {
 
-      foreach (NodeEdgePtr edge, param->edges()) {
+      QVector<NodeEdgePtr> edges = param->edges();
+
+      foreach (NodeEdgePtr edge, edges) {
 
         NodeInput* connected_input = edge->input();
         Node* connected_node = connected_input->parent();
@@ -298,7 +300,7 @@ void Node::Hash(QCryptographicHash *hash, NodeOutput* from, const rational &time
   QList<NodeDependency> deps = RunDependencies(from, time);
   foreach (const NodeDependency& dep, deps) {
     // Hash the connected node
-    dep.node()->parent()->Hash(hash, dep.node(), time);
+    dep.node()->parent()->Hash(hash, dep.node(), dep.time());
   }
 }
 
diff --git a/app/node/output/track/track.cpp b/app/node/output/track/track.cpp
index 936306a6c..277a1c95e 100644
--- a/app/node/output/track/track.cpp
+++ b/app/node/output/track/track.cpp
@@ -90,6 +90,11 @@ void TrackOutput::Refresh()
 
   foreach (Block* b, block_cache_) {
     if (!detect_attached_blocks.contains(b)) {
+      // If the current block was removed, stop referencing it
+      if (current_block_ == b) {
+        current_block_ = this;
+      }
+
       emit BlockRemoved(b);
     }
   }
diff --git a/app/node/processor/renderer/renderer.cpp b/app/node/processor/renderer/renderer.cpp
index d9b2872d3..0d04e35a6 100644
--- a/app/node/processor/renderer/renderer.cpp
+++ b/app/node/processor/renderer/renderer.cpp
@@ -96,18 +96,22 @@ QVariant RendererProcessor::Value(NodeOutput* output, const rational& time)
       return 0;
     }
 
-    QString fn = CachePathName(time);
-    if (QFileInfo::exists(fn)) {
-      auto in = OIIO::ImageInput::open(fn.toStdString());
+    // Find frame in map
+    if (time_hash_map_.contains(time)) {
+      QString fn = CachePathName(time_hash_map_[time]);
 
-      if (in) {
-        in->read_image(PixelService::GetPixelFormatInfo(format_).oiio_desc, cache_frame_load_buffer_.data());
+      if (QFileInfo::exists(fn)) {
+        auto in = OIIO::ImageInput::open(fn.toStdString());
 
-        in->close();
+        if (in) {
+          in->read_image(PixelService::GetPixelFormatInfo(format_).oiio_desc, cache_frame_load_buffer_.data());
 
-        master_texture_->Upload(cache_frame_load_buffer_.data());
+          in->close();
 
-        return QVariant::fromValue(master_texture_);
+          master_texture_->Upload(cache_frame_load_buffer_.data());
+
+          return QVariant::fromValue(master_texture_);
+        }
       }
     }
   }
@@ -122,6 +126,8 @@ void RendererProcessor::Release()
 
 void RendererProcessor::InvalidateCache(NodeInput* from, const rational &start_range, const rational &end_range)
 {
+  Q_UNUSED(from)
+
   qDebug() << "[RendererProcessor] Cache invalidated between"
            << start_range.toDouble()
            << "and"
@@ -136,17 +142,12 @@ void RendererProcessor::InvalidateCache(NodeInput* from, const rational &start_r
   for (rational r=true_start_range;r<=end_range;r+=timebase_) {
     if (!cache_queue_.contains(r)) {
       cache_queue_.append(r);
-
-      QString fn = CachePathName(r);
-      if (QFileInfo::exists(fn)) {
-        QFile(fn).remove();
-      }
     }
+
+    time_hash_map_.remove(r);
   }
 
   CacheNext();
-
-  Node::InvalidateCache(from, start_range, end_range);
 }
 
 void RendererProcessor::SetTimebase(const rational &timebase)
@@ -209,7 +210,7 @@ void RendererProcessor::Start()
   threads_.resize(background_thread_count);
 
   for (int i=0;i<threads_.size();i++) {
-    threads_[i] = std::make_shared<RendererProcessThread>(ctx, effective_width_, effective_height_, format_, mode_);
+    threads_[i] = std::make_shared<RendererProcessThread>(this, ctx, effective_width_, effective_height_, format_, mode_);
     threads_[i]->StartThread(QThread::LowPriority);
 
     // Ensure this connection is "Queued" so that it always runs in this object's threaded rather than any of the
@@ -300,16 +301,21 @@ void RendererProcessor::CacheNext()
   caching_ = true;
 }
 
-QString RendererProcessor::CachePathName(const rational &time)
+QString RendererProcessor::CachePathName(const QByteArray &hash)
 {
   QDir this_cache_dir = QDir(GetMediaCacheLocation()).filePath(cache_id_);
   this_cache_dir.mkpath(".");
 
-  QString filename = QString("%1.%2.exr").arg(QString::number(time.numerator()), QString::number(time.denominator()));
+  QString filename = QString("%1.exr").arg(QString(hash.toHex()));
 
   return this_cache_dir.filePath(filename);
 }
 
+bool RendererProcessor::HasHash(const QByteArray &hash)
+{
+  return QFileInfo::exists(CachePathName(hash));
+}
+
 void RendererProcessor::CalculateEffectiveDimensions()
 {
   effective_width_ = width_ / divider_;
@@ -322,14 +328,16 @@ void RendererProcessor::ThreadCallback()
     // Threads are all done now, time to proceed
     caching_ = false;
 
-    RenderTexturePtr texture = texture_input_->get_value(cache_frame_).value<RenderTexturePtr>();
+    RenderTexturePtr texture = master_thread_->texture();
 
     if (texture != nullptr) {
-      QString fn = CachePathName(cache_frame_);
+      QString fn = CachePathName(master_thread_->hash());
       download_threads_[last_download_thread_%download_threads_.size()]->Queue(texture, fn, cache_frame_);
       last_download_thread_++;
     }
 
+    time_hash_map_.insert(cache_frame_, master_thread_->hash());
+
     CacheNext();
   }
 }
@@ -347,7 +355,7 @@ void RendererProcessor::ThreadRequestSibling(NodeDependency dep)
 void RendererProcessor::DownloadThreadFinished(const rational& time)
 {
   // Check if we just downloaded (akak finished caching) the frame we're currently on
-  if (time == last_requested_time_ && texture_output_->IsConnected()) {
+  if (texture_output_->IsConnected() && time == last_requested_time_) {
     // Send invalidate cache signal to all nodes connected to the texture output
     QVector<NodeEdgePtr> edges = texture_output()->edges();
 
diff --git a/app/node/processor/renderer/renderer.h b/app/node/processor/renderer/renderer.h
index cbfd3c454..4a60717d6 100644
--- a/app/node/processor/renderer/renderer.h
+++ b/app/node/processor/renderer/renderer.h
@@ -83,6 +83,11 @@ public:
 
   void SetDivider(const int& divider);
 
+  /**
+   * @brief Return whether a frame with this hash already exists
+   */
+  bool HasHash(const QByteArray& hash);
+
   /**
    * @brief Return current instance of a RenderThread (or nullptr if there is none)
    *
@@ -126,7 +131,7 @@ private:
   /**
    * @brief Return the path of the cached image at this time
    */
-  QString CachePathName(const rational& time);
+  QString CachePathName(const QByteArray &hash);
 
   /**
    * @brief Internal list of RenderProcessThreads
@@ -175,6 +180,8 @@ private:
 
   RenderTexturePtr master_texture_;
 
+  QMap<rational, QByteArray> time_hash_map_;
+
 private slots:
   void ThreadCallback();
 
diff --git a/app/node/processor/renderer/rendererprocessthread.cpp b/app/node/processor/renderer/rendererprocessthread.cpp
index a44a8507f..ed323adfc 100644
--- a/app/node/processor/renderer/rendererprocessthread.cpp
+++ b/app/node/processor/renderer/rendererprocessthread.cpp
@@ -20,12 +20,16 @@
 
 #include "rendererprocessthread.h"
 
-RendererProcessThread::RendererProcessThread(QOpenGLContext *share_ctx,
+#include "renderer.h"
+
+RendererProcessThread::RendererProcessThread(RendererProcessor* parent,
+                                             QOpenGLContext *share_ctx,
                                              const int &width,
                                              const int &height,
                                              const olive::PixelFormat &format,
                                              const olive::RenderMode &mode) :
-  RendererThreadBase(share_ctx, width, height, format, mode)
+  RendererThreadBase(share_ctx, width, height, format, mode),
+  parent_(parent)
 {
 
 }
@@ -56,6 +60,16 @@ bool RendererProcessThread::Queue(const NodeDependency& dep, bool wait)
   return true;
 }
 
+const QByteArray &RendererProcessThread::hash()
+{
+  return hash_;
+}
+
+RenderTexturePtr RendererProcessThread::texture()
+{
+  return texture_;
+}
+
 void RendererProcessThread::ProcessLoop()
 {
   while (!Cancelled()) {
@@ -71,20 +85,27 @@ void RendererProcessThread::ProcessLoop()
     NodeOutput* output_to_process = path_.node();
     Node* node_to_process = output_to_process->parent();
 
-    QList<NodeDependency> deps = node_to_process->RunDependencies(output_to_process, path_.time());
+    // Check hash
+    QCryptographicHash hasher(QCryptographicHash::Sha1);
+    node_to_process->Hash(&hasher, output_to_process, path_.time());
+    hash_ = hasher.result();
 
-    // Ask for other threads to run these deps while we're here
-    if (!deps.isEmpty()) {
-      for (int i=1;i<deps.size();i++) {
-        emit RequestSibling(deps.at(i));
+    if (!parent_->HasHash(hash_)) {
+      QList<NodeDependency> deps = node_to_process->RunDependencies(output_to_process, path_.time());
+
+      // Ask for other threads to run these deps while we're here
+      if (!deps.isEmpty()) {
+        for (int i=1;i<deps.size();i++) {
+          emit RequestSibling(deps.at(i));
+        }
       }
+
+      // Get the requested value
+      texture_ = output_to_process->get_value(path_.time()).value<RenderTexturePtr>();
+
+      render_instance()->context()->functions()->glFinish();
     }
 
-    // Get the requested value
-    output_to_process->get_value(path_.time());
-
-    render_instance()->context()->functions()->glFinish();
-
     emit FinishedPath();
   }
 }
diff --git a/app/node/processor/renderer/rendererprocessthread.h b/app/node/processor/renderer/rendererprocessthread.h
index bb875defd..0953ea489 100644
--- a/app/node/processor/renderer/rendererprocessthread.h
+++ b/app/node/processor/renderer/rendererprocessthread.h
@@ -23,11 +23,14 @@
 
 #include "rendererthreadbase.h"
 
+class RendererProcessor;
+
 class RendererProcessThread : public RendererThreadBase
 {
   Q_OBJECT
 public:
-  RendererProcessThread(QOpenGLContext* share_ctx,
+  RendererProcessThread(RendererProcessor* parent,
+                        QOpenGLContext* share_ctx,
                         const int& width,
                         const int& height,
                         const olive::PixelFormat& format,
@@ -35,6 +38,10 @@ public:
 
   bool Queue(const NodeDependency &dep, bool wait);
 
+  const QByteArray& hash();
+
+  RenderTexturePtr texture();
+
 protected:
   virtual void ProcessLoop() override;
 
@@ -44,10 +51,16 @@ signals:
   void FinishedPath();
 
 private:
+  RendererProcessor* parent_;
+
   NodeDependency path_;
 
   rational time_;
 
+  QByteArray hash_;
+
+  RenderTexturePtr texture_;
+
 };
 
 using RendererProcessThreadPtr = std::shared_ptr<RendererProcessThread>;