Un-taggable MP3's.

As I have already told some of you before,
from time to time I continue tagging my MP3 collection,
correcting existing tags, completly tagging, puting the album picture, etc.
But on rare ocations, I stumble with some files that just won't ger tagged,
what I mean by this,
is that, they have no tags, so I procede to tag and save, but then, if I go and check the album, lets say, on Media Player, the tags are not there,
as if I hadn't done anything, and I can repeat the steps, and the files just won't get tagged.
*for tagging In using "Tag&Rename (ver. 3.1.7)

Does anyone have any idea why this might be?

right click your music folder then make sure read only is unticked then click ok and try again

Perhaps they're wma or ogg files with the estension changed?

Try tagging them manually in Winamp or something. I can't imagine why it wouldn't be taggable.