I tried to create an action and got runtime error finishing its creation (presing "OK" within a dialog titled "Actions"). The program not crashes but it's seems to be impossible to create any action in the current version.
AppPath: 351.764.480 Bytes frei (C:\Program Files\Mp3tag)
Can't reproduce on another (still XP) machine.
Probably the bug had raised because I removed all registry enries related to mp3tag and user profile files too just (to enable other language install) just before the "bug".
Marking as no bug then. If you should find out for sure what caused the bug, reply here and I'll change the status.