Drive Letter Disappearing in Windows Vista

If you have been having a problem with the Drive Letters disappearing in Windows Vista try deleteing the following Registry Keys. One of the iTunes updates seems to clobber the drive letters (in some instances). As always, be very careful editing the registry. It is a good idea to back it up first:
Step 1: In Vista search box on the start menu - type in regedit.
Step 2: Open Registry Edit (regedit link appears)
Step 3: Under Computer, open the folder for HKEY_LOCAL_MACHINE
Step 4: Then open the folder SYSTEM
Step 5: Then open the folder CurrentControlSet
Step 6: Open the CONTROL folder
Step 7: Open the folder "Class"
Step 8: Look carefully for the folder called
{4D36E965-E325-11CE-BFC1-08002BE10318}
Step 9: On the right side of the open panel, you'll see a listing with lots of information - NEXT to (Default) be sure it reads DVD/CD-ROM drives -
Class should be CDROM
Step 10: There are two files called UpperFilters and LowerFilters. Delete UpperFilters first by clicking the delete key, then say yes. Repeat the process with LowerFilters.
***Be sure the files you're deleting say only UpperFilters and LowerFilters, nothing else.
Step 11: Restart your computer.