It's nearly ALWAYS a codec issue:
Download and install G-Spot from
http://www.headbands.com/gspot/
Once you analyze the AVI file, it will tell you with which codec it was
compressed. An uncompressed AVI file is over 12gb per hour, (yes, GB not
mb) so it is highly unlikely you have an uncompressed AVI file. A
compressed AVI file needs to have the correct codec installed on your PC
BEFORE it will play correctly.
The two most common codecs are DiVX and XVid.