Quick Time files causing crash.

[Droog]

This is a relatively new problem for me. It has gotten unbearable. Every few minutes or so Pro Tools locks up and I have to restart. The GUI locks up, shows that PT is not responding, the audio continues to play, but interface is froze. It only happens when I try to stop playback, and seemingly it only happens when i am working with a quicktime movie in the time line.
Also, I am working from OMF which should not be causing any problems, the audio is there and working fine, I really don't think that is the prob. Last night working on music only without video it was fine, but as soon as I try to edit to picture it becomes useless.

Any clues? If anybody has any ideas I would be greatly appreciative.

Thanks a lot,

Phil