Trend Micro Rescue Disk is a free tool which creates a bootable malware-hunting package on a CD, DVD or USB key.
This kind of antivirus approach takes more time and effort to set up, but it can also be far more effective at removing more stubborn and stealthy threats. Boot from the Trend Micro disk and you can be sure any malware is not running in the background, giving it less opportunity to avoid detection or interfere with the scan.
The download arrives as a setup wizard, rather than a disk image, making it very straightforward to use. There's no need for additional software, just choose where to create your rescue disk - a hard drive, USB key or optical disk - and the program will handle it for you.
Please note: the target drive will be reformatted and any existing contents lost. Choose it carefully, and double-check to make sure you're not going to wipe anything important.