To enable registry editor that was disabled by some malware please do the following to regain access and perform maintenance:
Some malware intentionally disable or hide Folder Options to prevent users from deleting files related to it.
One of the most successful ways to scan a computer is by scanning it without booting on itself. This can be done by removing the hard disk and attaching it to a clean computer and make a thorough scan. This way, the virus has no chance of residing into memory.