Rootkit Removal From Non Booting Computer by Britec
rootkit removal on Windows systems, rootkits are being used by spyware, adware, viruses, trojans, and other malware to hide the system processes as they work undetected. Slow running computers, unwanted popup ads, google redirects of websites can all be signs of a rootkit. it will take special software to detect them on the system. Since rootkits are designed to hide from users they also hide from most antivirus and antispyware software. This is why many of the antivirus makers have produced rootkit removal tools.
if you are still having issues including blue screens, system slowdowns, and other problems and none of your virus and spyware tools have detected a problem, you might have a rootkit. Safe way to be sure is to format the operating system.
more info can be found here