Hi Florian,
Mp3tag is crashing on me when I look up an album via Musicbrainz (most recently, "Murs 3:16 the 9th Edition"). It doesn't happen on every album I look up, just on some, and only some of the time (so it's not entirely reproduceable). I was using 2.37d before, and it never crashed on me (or any previous version for that matter), so I think the bug was introduced in the latest builds. Let me know if you need me to send you the crash report. Oh yeah, this is on XP Media Center 2005 w/SP2.
-Will