Video file (avi) generated in Materials Studio 8 does not play on Windows

I recently used Materials Studio 8 to generate a video file (avi) from a molecular dynamics simulation. However, I cannot get the movie to play using Windows Media Player or as an embedded file in PowerPoint. The error message is not helpful:
Windows Media Player encountered a problem while playing the file.

I have done this many times using previous versions of MS. Why is this not working?