Question : No system sound

I have no system sound, can't play .avi or mp3 files. I Can play .wmv and .wav files.
I get this message but can't find the codec:

Windows Media Player Error Message Help
You've encountered error message C00D10D1 while using Windows Media Player. The following information might help you troubleshoot the issue.
Codec is missing
Windows Media Player cannot play the file (or cannot play either the audio or video portion of the file) because the MP3 - MPEG Layer III (55) codec is not installed on your computer.
The missing codec might be available to download from the Internet. To search for the MP3 - MPEG Layer III (55) codec, see WMPlugins.com.

Phil

Answer : No system sound

Sounds like you specifically need the Fraunhofer MPEG Layer-3 Audio Decoder  (a3codecx.acm) rather than a full codec pack.