I've been using mediacar for awhile without any problems.
I recently installed XP SP2. Since then (I think), Mediacar hangs for a few seconds while playing mp3's. the 'time elapsed' display will stop ticking, then a few seconds later, the mp3 stops playback, then everything resumes a few seconds later. It does it on every song. It does not have the problem when playing directly from winamp. I've tried re-installing to no avail.
edit: re-installed some more and solved it