Jeg fandt dette på nettet, prøv at se om det ikke virker! :-))
Response to AVI file with sound in “Windows Media Audio V2” format
I had the same problem: AVI playback but no sound. I have found the solution!
Download this codec pack:
http://www.divx-digest.com/software/nimo_pack.html Then install it selecting only the Audio Codecs. Now playback is fine, but to prevent this from happening again I have reencoded my video files to MP3 using Virtualdub.