I'm extremely OCD when it comes to organizing my music so it annoys me greatly when things like THIS (see below) happes:
I prefer using WMP.
I am very annoyed that I can't get rid of the embedded URL that appears every time the file is played. I've tried clearing all the tags with MP3Tag but that doesn't even work.
How did you try to clear ALL the tags? Just in the tag panel or did you open the extended view with ALT-T?
it looks to me as though you have the subtitles or lyrics turned on in WMP and that some source has written to these fields.
Have a look at a file that shows the unwanted URL using the extended tag view and you will find the compromising field which you then can delete (not clear).