Hi Hybelkanin, I suggest you to delete all tags with a tag killer

, for example ID3 Tag Killer (http://www.gd.co.yu/english/web.php?id=6) and rewrite them... I know it is annoying, but i think it's the only way to fix it.
The problem may have been caused by a software that doesn't use standard id3 tags, but it's hard to say... I suggest you to tag with id3-tagit (http://www.id3-tagit.de/), which is very stable, compatible and freeware (but unfortunately it needs .net framework...)
And, finally, avoid using multiple softwares to edit tags

, there are various versions of id3 (1.1, 1.0, 2.2, 2.3, 2.4) and not every software support them all
Bye