Try getting G-Spot and using it to look for Codec problems: Here

For more info on this tool and codec issues, please check a previous post of mine here.

Please also take note when using the tool, of the codec it actually uses to run the video, and which codec the video is actually encrypted to. Should G-Spot tell you it runs well on one codec, but the video seems to be encoded to a different codec, change it to the codec the G-Spot tells you it works with.

EG: I recently downloaded AirMaster Ep 21. It kept crashing my WMP and my Windows Explorer everytime i tried to play the file. So i checked the details in the microsoft debug info and found the problem appeared in the Xvid.dll file. I then diagnosed the file in G-Spot and found that it should of been run on the DivX file and not the Xvid file. I solved this problem by using one of the Xvid codec tools, to change the codec the file uses from Xvid to DivX. (This file is known as fourcc).

Please make sure the debug info refers to the same file as the one G-Spot refers to, otherwise the file has been incorrectly encoded.

I am unsure of where you could locate the fourcc tool, but my guess would be here. If it is not, then i really have no idea, but i could email you it if you wanted?