I was trying to install the newest version and whenever I did it said it was unsuccessful because mp3tag was still running but it actually wasn't(made sure nothing was running in task manager, etc.). I tried to uninstall it and the same thing happened but it actually did manage to uninstall after a few tries. Now I am unable to install the damn thing.
Can you try it using an Administrator account? It sounds like the user account you're operating with has not enough permissions to install/unistall Mp3tag.
It worked, thanks