Well the problem its not if I can change my file's comment, I had already tested it on an image a couple of days ago and its still there with my comment not changed.
The problem is changing over 2000(and its an optimistic estimate) file's proprieties back to their original comment (which in most case isn't possible since the original info its gone, gone forever), but what makes me really wonder if what's changing or altering the view of my file's proprieties, since as I said I have recovered some image libraries from over 2 years ago's backup and some of their comments was altered.