We only have a few working XP machines left for production testing and when I see this it usually is the same in the tag editor. Digging deeper I find the user had downloaded from somewhere and the mystery is over.
There are some rippers and files that have odd tag fields with non-standard formats that will trigger this issue. No fix will ever be seen for reasons I'm sure we don't have to discuss.
I apologize but why didn't you use google or download.com to look for another editor?