iMovie and memory

[hazmat]

How does iMovie deal with memory? I was importing some DV last night, and stopped at a certain point, but left it open to start again tonight. After a certain point tonight, before touching iMovie, every newly opened app would freeze, with the exclamation mark over its icon in the Dock. I couldn't figure out what was wrong, but when I clicked on iMovie, it had a message about there being no more memory. After that I couldn't do anything but force quit Finder, which would come back with the beach ball again and again. I had to do a hard reboot. Was this iMovie's fault? I have 896 megs of RAM, so I figured it shouldn't be a big deal to leave it open. Only good thing about this was that when I opened iMovie after the reboot, expecting the imported videos to be gone from the project, it actually said that the 5 stray clips were there, and it would put them in for me to decide what to do with them. Very nice.

Thanks.