Zaphod,
Here's something you could try; a way of out finding what codecs are used when playing audio files like mp3 are using a free tool like GSpot:
http://www.headbands.com/gspot/download.html
It's a bit technical but here's a quick walkthrough;
In GSpot, go to the File menu, then Open -> Select an mp3 file (any will do I think), click Render (bottom), then look at Audio Path there and you should get the name of the codec windows uses to play the file.
Also, click on the 'Status' line and then the name of the filter for info on where the offending file is located on your system.
Then go the the windows Start menu -> Run, type 'regsvr32 /u
path to codec file' and the codec should be uninstalled.
Hopefully the game will then use your the default, MS-supplied codec for mp3 playback.
Hope this helps you to finally enjoy the game!
Stian