Not playing AVI files

When I run my DirectRT .csv program, the video files are not showing up. All that appears is a black screen. The files are .avi, and they play successfully when I open them with Windows Media Player. The .csv program works when I replace the .avi files with text instead.

The .csv file (with .avi stimuli) worked successfully when I tried running it on a different computer. Both the failed and successful computer were PCs. Are there computer-related issues that might be causing the .avi files not to play on my computer?