I hope, you do realize that this looks a lot like a problem of your local settings and has nothing to dowith the mp3 tagging process. Windows Explorer is no tagging program, Mp3tag is - and as that works fine, why bother about WE?
Anyway: check if you are the owner of those files - "Administrators" does not look right to me.
Did you import that folder from an old XP installation? Then you should claim ownership again.
See this thread for a Microsoft support page on changing the owner.
mp3tag on windows 7