XVID to Divx

First off, make sure you've got an up to date version of xvid. It might just be trying to use a vfw codec that isn't quite compatible with the xvid your stuff is encoded in. I doubt this is it, but it'll be important for the later options, so do it anyway.

tmpeg tends to work better than a lot of other things for converting straight to mpeg. Have you considered using it instead?

If you must use your current program (which from the other thread I saw you in I'm guessing is premiere) you might need a newer version, or it might just not support xvid at all. You might look into plugging avisynth into it (if it can understand avs scripts ... but if it does, then it'd probably understand xvid anyway). Then, if it doesn't understand xvid, it probably isn't on speaking terms with frameservers and such either, so.... ya know.

You might be able to 'cheat' and save some time. Back up your file before you do this (just make a copy of it and work in the copy), and you can try changing the fourcc using either "AVIC" or "Nic's Fourcc changer" from your xvid folder from the start menu. Change the fourcc's both to "dx50" and save it, and see if it works. Your mileage may vary, depending on the original encoder's settings, so make sure stuff works if you do this method. The big sticking points for this one would be qpel and gmc (quarter-pixel support and global motion compensation) -- if the encoder turned these on they won't play nicely with divx5 anymore.

If you absolutely must convert xvid to divx (in other words the previous method didn't work), you'll need virtualdub (or virtualdubmod). Install both xvid and divx codecs and your preferred flavor of virtualdub, open the xvid video file, go to compression and pick divx, configure it as you desire, do "fast recompress" and audio direct stream copy (or whatever you want to do with it). Save the new file, and watch it spend a good chunk of time converting. In a good case, it might go in real-time or a bit better (20-40fps). In a bad case, it might go extremely slowly (<10 fps). Note that the previous method is basically instantaneous, where this will always take at least a little while, which is why I recommend trying the other one first. This method will be a sure-fire one though, as long as you've got the codecs installed.