How to remove virus in keyboard?

when i'm typing, characters automatically pop up like "b\\*" and the right-click menu. also when i go to start menu it automatically scroll up to 'notepad' and opens it! also num lock toggles off and on by itself.i have nod32 and uniblue, both detected no errors. i also did a system restore, but i did it to restore after windows xp sp3, which i installed like days ago... maybe the sp3 have problems. oh ya. this is dell dimension 2350. will buying a new keyboard get rid of the virus?(if it is virus)