I'm getting no errors in the output log and have 2GB of RAM.

I tried the render again yesterday and it didn't include particles until frame 128. At frame 128 they were perfect -- in the right places and everything.

They disappeared after frame 168, never to be seen again...

I hate this I hate this I hate this.

I'd scrap the whole thing, since I'm just experimenting with motion paths, but it really annoys me that I can't figure out what's wrong.