Final Cut Express 3.5 HD quits unexpectedly
The problem was with the cross-dissolve transition that I was trying to render. Technically, I haven't figured out the problem, but now I know what is causing the problem. I am able to render video in other sequences and that works just fine. I haven't tried rendering a cross-dissolve transition in another sequence. Thanks so much to bmike for helping me with this!

UPDATE: I have tried rendering other cross-dissolve transitions in other sequences and even in the same sequence that had a problem. It was only that edit that was having a problem. The cut that I had placed the transition on was a full 1080p video. I don't think my version of FCE likes 1080p video. When I try to do other stuff to that clip, it wil sometimes quit.