Cannot Read Files From CD Backup…

I recently backed up some customer data onto CD. When trying to restore .pst file and “My Documents” folder, recieve errors such as…”unable to access files” , or “You do not have permission to access this file”. All the files and folders attributes are readable from the CD. i.e: file size, date modified etc. I have used the CD-burner in question many times before and since, with no problems reading data. I have never seen this problem before, does anyone have any insight?