It might be the codecs, try to update them.
If it doesn't work then you will probably need to encode them with the DivX codec. You can do that with the VirtualDubMod using the option "save as" then selecting
"Save as type": Audio-Video Interleave (*.avi)
"Video Mode": Full Processing mode
"Compression:" (click on change and select DivX5.5 codec)
I hope that helps.