
I worked around the problem by installing a codec called "DS-MP3 Source Filter":
http://www.free-codecs.com/download/DS_MP3_Source_Filter.htm
This codec replaces the AsyncSource Filter and MPEG-I Splitter from Quartz.dll and the standard (old) Fraunhofer MP3 decoder. It uses the Bass.dll library for decoding MP3's. Other media types will still be processed in the normal fashion.
B.T.W. Installing DS-MP3 also fixed a problem on a friend's machine where playing certain VBR MP3's with Lister caused TC to hang. Even GraphEdit was hung up by these files.
Thanks for your input guys.