You likely don't have the right codec installed for that specific AVI or you have a bad install of the codec.

Using a DirectShow decoding filter such as FFDShow will decrease the problems you could run into with codec problems.  FFDshow will decode XviD, DivX 3/4/5, 3IVX, and has support for many other codec's.  It can be downloaded at http://sourceforge.net/project/showfiles.php?group_id=53761&package_id=48261&rel
ease_id=95213. (Download ffdshow-20020617.exe and then run it's installer)

If you have the correct codec installed and the video still doesn't play download GSpot (Below) and run your AVI though the program.  If Gspot says "Failed to render", "Missing Chuck", etc. then your video file is corrupt.

If you just wish to install the individual codec's for your specific video or FFDShow doesn't support the codec for you file please do the following.
- Download and use GSpot (http://www.headbands.com/gspot/download.html)
- Run the installer, open GSpot, goto File>>Open.
- Look for the 4CC code for the file's Video Codec
- http://www.zachd.com/pss/pss.html#codec will help you.
(Or post the information back here and I can help)
-If you don't get audio, what codec does it use?  GSpot also tells you this.

Regards,

Shadow