Check that you have the right codecs. I remember i had a similar problem because the file was coded for another codec but the system was using another. Best codec pack to use in my opinion is either the Codec Pack (quick google should get you the link) or Ace Mega Codecs Pack (similarly found via google).
If that doesnt work, make sure you have the latest drivers and try and boost the gamma from the overlay settings.
Anyway, hope this helped at least a bit.
Mufitman
Edit - Just read that properly, yeah i think its a codec thing. Cos i had that ffddshow instead of XviD. Uninstall all the codec packs youve got on your pc, restart and then install the ones from the codec pack - those are the ones im using atm, and they seem to be running perfectly.