MM2 limit on number of slides?

I tried to create a movie with about 800 slides (~40 minutes with 5 sec/slide and transitions). I have a fast machine (2.8Ghz hyperthreaded P4, 1GB RAM, 200GB disk, 3GB swap), but once I added the transitions and music, MM2 slowed to a crawl. In an attempt to make it more reasonable, I split it into two shows of about 400 slides each. It helped, but not much.

But here's real problem #1. When I tried to save the movie as avi, I got a "not enough disk space" message even though I have scads of available space and the swap is distributed across physical disks. I was able to save the movie as wmv.

And here's problem #2. The first movie shows the first 238 slides and then gets "stuck" on the 238th slide even though the music continues. The second movie gets "stuck" after 134 slides and shows black (even though there isn't any black with the transitions I used). At first, I blamed the DVD burning software, but it's the wmv file itself--confirmed by using windows media player.

Any ideas about what's going on?

RobertJ