I have a virus that runs even in safe mode. I have scanned with AVG livecd and removed infected files including winlogon.exe and atapi.sys. I replaced thosed files with copies from an uninfected computer. After rebooting, antivirus caught another virus infecting the winlogon.exe file. I stopped the system restore service and set it to disabled and rebooted and the system is in an endless loop of restarting even when attempting to boot into safe mode.