FCP 7 crashing

I am experiencing crashing with FCP 7, I have a 60 minute HD show and have some clips that are mp4. I understand these clips are hard on FCP 7 and may be the cause of the crashes. Also, even though I render the entire project, when it crashes and I re-open the project, many of the clips need to be re-rendered again. Very frustrating. ANy ideas why? Thanks.

FCP 7
MacPro
OS X 10.6.8
2,15 GHz Intel

is it the mp4 clips that require re-rendering?
you might have to bight the bullet and go ahead and convert them to Prores.


nick

What Nick said, and make certain your renders are NOT being routed to your system-boot disk, which is normally busy reading and writing system and app resources, but to a distinctly separate scratch disk, either where primary captures are stored or routed into a Render Files folder on that or on yet another scratch disk.

Best, as always.
Loren S. Miller