tags not updating

I have a strange thing happening. I am trying to change tags on a Mariah Carey CD (either automatically or manually) but despite showing that the updating is happening, when the operation completes, the tags have not changed. I've tried it on 2 different computers and both show the same thing.
So somehow the tags seem to be "locked" - is this possible and if so how do I solve this problem.

Thanks to anyone who can help.

On the less serious side: Mariah Carey tracks are not worth the tagging. Just kidding.

Check if the MP3s are tagged with something else than MP3 Vxxx - APE tags are usually the culprits.
You check this by selecting a track and press Alt-T to see the enhanced tags. The then opened dialogue displays teh types of found tags in the window title. If this shows APE then there you are.
Next: change MP3Tags options (Extras: Options: Tags: Mpeg) from writing APE to not writing APE. This should cleans all APE tagging from the file and suddenly all your MP3Tag modifications are visible. Apparently APE is superior in hierarchy (not function) to MP3 and overrides MP3 tags.

Mariah Carey tracks are not worth the tagging<< Ha, Ha - my wife would agree with you!

Your solution worked perfectly - thank you very much. Now that I have done as you suggested the tags update correctly. You're a star!