Just in – Sophos Anti-Rootkit – now with 64-bit and Windows 7 support – a free download from Sophos
Another tool to go in your software toolkit along side MalwareBytes and HijackThis and the ubiquitous Autoruns. Storing updated copies of these applications on a USB key for action when you come across an obviously infected machine – or a not so obviously infected but troublesome machine is a good idea !!!
As Sophos say
Our free software, Sophos Anti-Rootkit scans, detects and removes any rootkit that is hidden on your computer using advanced rootkit detection technology.
Rootkits can lie hidden on computers and remain undetected by anti-virus software. Although new rootkits can be prevented from infecting the system, if you had any rootkits before you installed your anti-virus, they may never be revealed.
Removing rootkits without compromising system integrity is particularly challenging and needs to be done with care.
Download a free copy of Sophos Anti-Rootkit 1.5 now.
http://www.sophos.com/blogs/gc/g/2009/08/10/sophos-antirootkit-updated
http://www.sophos.com/products/free-tools/sophos-anti-rootkit.html