why does my keyboard not work in safe mode?

I am struggling with System Security Virus on my Windows XP SP2 computer. When I contact Microsoft for help they suggested me to run Antivirus scan booting in Safe Mode. But the problem is when I boot into safe mode my keyboard stops working it. None of its keys works.

Any idea why is it not working in safe mode?

If you are using the USB keyboard, then enter BIOS while bootup and set the BIOS for legacy USB devices. Then only it will work.

Thanks for the help prash_mate, but it is not USB keyboard, its PS2. One more thing I noticed after posting here the query that even my mouse is not working in safe mode. Yeah, its too PS2. To check the problem is with system or mouse, I connected a USB wireless mouse and tried using, it works fine.

I think instead of talking keyboard and mouse we should get to the point that is virus infection on your PC. First of all you should download Microsoft Malicious Software Removal Tool and scan the system completely. You can download the same form here http://www.microsoft.com/security/pc...e-removal.aspx. If that wont work, than Run the Windows Live Safety Center's 'Protection' scan (only!) in Safe Mode with Networking

If none of these can clean your computer then the only way left is to do a clean format of your windows because even windows repair cannot fix the infection.