Hmmm. I have a Mac....this is my first vid made on Final Cut Express as opposed to iMovie, but I exported it the same way as all my others, as a DivX. I just went back to FCE and checked - there is a codec tab amongst the DivX Advanced export settings, but I didn't change anything in it.

WHY, TECHNOLOGY, WHY DO YOU HATE ME?

I'm sorry I can't be more help :-(