alright, i don't have much time so i just write something brief
DivX can have a number of problems, most of the time it is missing segments when you are downloading or the file originally is broken with missing stuff.
there are a number of things you can do
there are 2 programs which i recomend you try out in order to fix dive files that cannot be openned
one program which i swear by all the time is called 'Virtual Dub" be A. Lee (can't remember his whole name), one of the very fix free/shareware divx encoders
open the file using virtual dub, if you can't then the file is pretty much dead and nothing can be done about it
you can fix broken files by saving it again in divx using virtual dub, just select 'direct source copy' for both audio and video... and then save as .avi again
another program you can try to use which doesn't work as well is called
DivFix103
it pretty simple and once you open it just play around with the only 2 buttons you can't go wrong
these's probably a couple more programs but i can't remember them off the top of my head....nor do i have the time to go into them sorry
hope this helps....