I got rootkit'd over the weekend and spent most of Saturday trying to shut the trojan down. Malwarebytes wouldn't run. I tried to reinstall and the reinstaller kept crashing. My anti-virus programs couldn't access their home sites to update themselves. Browser was hijacked. The computer was basically useless. I couldn't even really download anything, but I could transfer files over from another computer on the network that I used to download installers.
Anyway, the only thing that ultimately worked was making a Linux boot disk with a strong anti-virus sweeper. It worked perfectly.
http://www.avira.com/en/pages/index.php