I had the same problem. I experimented a bit and managed to get one project to export, but in order to get it to work I had to remove the audio track.
The audio tracks I had been using with it were ripped into Apple's lossless format, so I don't know if that had anything to do with the crashing or not. I haven't tried MP3 or AAC audio with it yet.
I reported the problem to Roxio and sent the crash log several days ago. It has been escalated to tier 2 support, whatever that means, but it has been several days since I've heard anything. Obviously this problem isn't uncommon.
It's very frustrating.
G4 Mac mini, OS X 10.4.6