Since we're dealing with an obvious infection, you'll want to redirect your attention to the security subforum here at SF. Link to this thread for reference, and follow the instructions for posting there to the best of your ability.
Otherwise, personally I would consider using a LiveCD environment like Parted Magic
, retrieve and backup your critical files, and then reinstall Windows, doing a complete reformat of the system drive, and start back from scratch. Afterwards you may wanna check (not fix
, but check) using a rootkit checker like Kaspersky's TDSSKiller to verify we aren't dealing with a rootkit (some rootkits will not go away from disk reformats).
This is one of those times where one becomes acquainted with the wisdom that is establishing a backup solution. It's not necessary for any PC, but if you have production files like what you mentioned on your system that cannot be lost, you must
setup at least a rudimentary backup and recovery system.