Oooo regedits..... I have a version of Win PE with all my "required" applications (regedit, msconfig etc.... lemmings lol) on CD. It's a bootable OS of CD/DVD and many variants are available. Ideal to remove protected files or reg keys.
Just used it to DE-ZOMBIE a laptop of mine..... my bloody A/V had been disabled by a mailer script that then installed trojans galour, protecting certain files, services and reg keys. Only fix was reload or rep the damage without booting the native O/S.