What program are you using to play those files?
Windows Media Player, WinAmp, RealPlayer, Quicktime and a few others. All of these programs are the most recent version. Also, the same effect happens when I try to play video games.
The only things that seem to work are YouTube videos on the Internet and .flv files on FLV Player 2.0. In addition, streaming audio from music sites such as Pandora.com seem to work.
This information would be helpful ...