Could be a graphicscard issue.
Latest driver installed?
Or roll one back.
Thanks for contacting adobe forums,
need few information about the system ..
What is the OS and version ?
What is the Graphics Card installed on the system ?
How much Ram do you have ?
Do you use any external Hard Drive ?
one more thing, if you are using mercury playback engine, try to use this on the software mode only
Please let us if it works or not.
It was indeed the Mecury Playback Engine playing up! Interesting, I am on OS X Mavericks which could be another factor to the problem.