Ok guys, I attempted several system restore points back to Nov 18th, and the problem still exists. When I attempt to restore to a date EARIER than the 18th, I get a message that reads: "Changes made to Drive(s) G after this point cannot be reversed because the drive was either excluded from System Restore monitoring, or was turned off or removed".
Here is the list of letter drives attached to my computer:
A: Internal Floppy Disk Drive
C: Internal Hard Drive (40 GB)
D: Internal Removeable Zip Drive
E: Internal CD-ROM Drive
G: External USB Plextor DVD/CD Drive
H: External USB Thumb Drive
Because 'drive G' is a removeable media CD/DVD burner, which doesn't include eraseable (changeable) data like the internal HD on the PC does, can I safely perform a system restore back to a point EARLIER than 11/18th?
I'm wondering if this message may be a clue to the problem. I somehow remember one of the drives being lettered 'F' at some time. Perhaps the computer's automatic drive letter 're-allocation' after a new removeable drive is added or removed, may be what lead to this problem?! What do you computer experts think?

Scott