Many of the best antivirus providers offer a no-cost bootable rescue disk to disinfect your computer after an infection. These are essentially Linux-based tools designed to clean an infected computer that won’t start or cannot be scanned from a normal antivirus software running in Windows. I recommend the Kaspersky disc for its ease of use (though it might not work on certain Dell systems).
Alternatively, you can get the same features from the Avira and ESET rescue disks, which include a user interface with graphics but require an external CD or USB device to start. Both of these options will analyze and detect any malware on your system. However the virus definitions may not be updated as frequently as the Rescue Disks that are Linux-based.
The Trend Micro rescue disk is another great option and one of the smallest options on this list with around 70MB. It doesn’t come with a graphic user interface but it works quickly and provides a number of customization options including the capability to scan and mount specific files, drive volumes and even specific folders.
Additionally, you can obtain a good virus scan from the Comodo rescue disk, though it’s not quite as flexibility of the Linux-based options above. It’s a highly effective tool for detecting and eliminating the type of viruses that hide in Windows files, and thereby preventing detection by normal antivirus software. It is possible to choose a text-only interface or a full-graphical interface. You can also perform a smart scan, or a custom scan.