It's a bastard that one. It blocks internet access, the registry, Anti virus sites, even task manager is disabled, etc. It infects everything new like .exe et al. How did I defeat it. I got to use "Process explorer", a sort of better "task manager" which I ran over my network (Stick will also do), with it I suspended (not kill) all "funny processes" running eating cpu time. If you kill the process then the virus deliberately shut you down. If you suspend it it is fine. Then as Internet and anti virus sites are blocked and damaged deliberately I battled to get the online antivirus scanners working. AVG free and Microsoft essentials would not install. So I downloaded "Trend Housecall", a small .exe which I ran of a stick. This then pulled its required files of the net. Detected the damage and fixed/deleted what was required. I then discovered another remover from AVG called rmvirut.exe Also ran this from a stick and it killed most of the issues. Then I had to do a XP repair as the VirutX saw its losing the battle and damaged the "winlogon" process (clever bugger) and the PC would only reboot after I punched in the password. One I got going it was still not the end. I managed to restore internet functionality and then could download and install/run AVG free and Microsoft essentials (together). That broke the camels back as all new infections got blocked giving me time to repair the damage. Then ran Malwarebytes/SuperAntiSpyware and both found some more vermin. BTW in all this the virus Mazebat was also doing it's thing.
Done all this for my neighbors son.
So yeah the quickest is reformat else use the weapons available at your fingertips.