After updating GPU, movies are shown dark while editing
When NVIDIA GeForce driver was updated to the latest 340.52,
movies are shown dark while editing.
Also, you may not find CUDA options.
The problem cause is under investigation. (as of August 1, 2014)
Please go to http://www.nvidia.co.jp/Download/Find.aspx?lang=en
and roll it back to the previous version 340.43, 337.88, etc. in the mean time.
Update: March 16, 2015
LoiLoScope126.96.36.199 is ready to fix this problem.
Note: You may see slightly higher CPU usage with this version, so it is highly recommended this to be used for NVIDIA users only.