Keyboard problem Help to troubleshoot.

Hi friends,
Few keys in my keyboard will not give the curresponding charector. Instead it gives a different charector. This problem is affected to
q, page up, page down, 8 (in the num keypad), space, some arrow keys, delete, ! etc.
Other charectors are OK. I partitioned my computer to both windows and linux. This problem occures for both windows and linux. I rechecked PS-2 keyboard port and updated new driver from the manufacturer's website. No use. There is no problems for other devices. Is it serious? Virus? Help me. I am including some events that I have done these days.
1) I cleaned up some registery files from windows system32 folder.
2) Uninstalled some softwares and installed some new.
3) I deleted some virus affected files.
Thanks.