Comments Tag ?

Hi, I use Tag&Rename to tag my MP3's.
But have noticed that some files are being left with a load of digits in the comments tag, even though there is nothing in the comments field in Tag&Rename.
I only see them when I right click on the properties of the file and look at the comments field there, by the way this is the only way I can find to delete these digits.
Any ideas or any help would be very grateful
Thanks