If you get a virus, the first step you usually take is running an anti-virus scan. What happens if your anti-virus is disabled or even uninstalled by the virus? Yes, some computer viruses are quite nasty, especially malware. These viruses are designed to make it look like your anti-virus is running, but as soon as you try to use it, the program crashes. First of all, don't panic. You can remove the virus. It just takes a little extra effort.
Safe Mode
Start by attempting to use your anti-virus via Safe Mode. Restart your computer and press "F8" during start to view boot options. For Windows 8, hold down the "Shift" key while pressing "F8." Select "Safe Mode." Do not enable networking. Try to run your anti-virus program again.
Install New Anti-Virus
If your anti-virus is still useless, boot into "Safe Mode with Networking." Download and install a few anti-virus of your choice. AVG, Avast, Avira and Comodo are just a few of the many options. Run a full scan, not a quick scan. For most viruses, this should take care of the problem.
Portable Anti-Virus
Sometimes Safe Mode just doesn't do the trick. For this option, you'll need to find a clean computer to use. Ask a friend or family member if you can use theirs, use your work computer or visit your local library or Internet cafe. You'll also need a formatted USB drive. Download and install a portable anti-virus program. I recommend AVG Anti-Virus Rescue , though you have a quite a few options available. If you have a favorite anti-virus software, check the manufacturer's site for a portable or USB version.
Boot your computer and insert the USB drive. Run the newly installed anti-virus software to detect and remove the virus.
What Next
Once the virus is gone, uninstall and reinstall your regular anti-virus. Uninstalling removes any glitches left over from the virus. After that, ensure you always run regular scans and avoid any sketchy emails or websites.
via Examiner National Edition Gadgets & Tech Channel Articles http://www.examiner.com/article/how-to-handle-a-virus-that-disables-your-anti-virus-software?cid=roadrunner