If I understand your last line well, you say that the problems stay after a clean install of Windows, even with another keyboard.
Then it's time for a radical change:
1. Another type of keyboard (USB in stead of PS/2 or the other way around)
2. Another OS (try Linux in stead of Windows)
3. A new motherboard.
I am using iBall Keyboard.
I have issue with my keyword when ever I press any key on my keyboard a "++++++++++" keep on going without press it.
Even when ever I open chrome same thing happen even when I click start button same thing happen.
I am facing this issue since week. i had same issue previously but it was solved(don't know how) but now again it is giving error.
I think i am facing this issue after installing superantispyware.
Even when i click windows key my PC shutdown automatically.I have not configure any thing.
Even formatting and changing keyboard doesn't help.