Hmmm...I just had this happen to me about a week ago.
I could still burn files, but I had a problem copying files from a CD/DVD disk to another location.
Although the "access denied" irritated me, I worked around it until yesterday, when I saw your post and decided to try to correct it
In addition to removing the upper and lower filters in the registry...I also right-clicked on the drive in My Computer and verified the Autoplay and Recording options in Properties. All seems well today.
Upper and Lower Filters. CD-ROM 314060 - http://support.microsoft.com/kb/314060