I am editing a music video project and at random the video will stop responding - the audio will continue playing but the video will freeze - there seems to be no way to recover from this scenario which has happened on this project 40 - 50 times already - the solution right now which is a nightmare is to SAVE / FORCE QUIT (as it will not simply quit but freezes) restart the MAC reboot the MAC / ADOBE / THE FILE and then I get maybe 10 minutes of editing done before the freeze happens again at random.
My iMac has 30 gigs of RAM there should be no issue with memory and all the footage is on my internal hard drive.
A little bit more about your machine would be nice ... is this all on a single drive, OS, programs, footage, cache, preview files, everything? If it is the amount of RAM you may have doesn't matter ... you'd have so many roadblocks & chokepoints going on in read/write/processing hashing that it wouldn't be surprising it does a bunk every once in a while.
Also ... past the whole OS/CPU/RAM/GPU/vRAM, drive numbers & layout of project parts on them, it would be good to know the type of codecs/formats involved, number of tracks of video & audio (audio can be very processor intensive, btw ... ) and all effects you're using.