Ps2 mouse and keyboard problem

One of my neighbour having bought a new computer 4 months back is having a strange problem with his keyboard and mouse both being ps/2. The mouse on windows xp loadup sometimes responds sometimes not. The keyboard lights up (the 3 indicators) when bootup, but at the post screen, it shows 'keyboard error, press F1 to resume' message. If he exchanges the placement of the keyboard and mouse, the keyboard is not even detected and the mouse works. He called me for an inspection, but i too can't make head or tail of this ghostly matter. I suggested him to buy usb keyboard and mouse.

Any suggestions what seems to be the problem with the system ? Is it possible that the 2 ps/2 ports are damaged somehow ? Then there is no way to use ps/2 products in here right ?

He has an intel dual core 2.2 ghz, intel G33 mobo, 1 gb 667 mhz ram, 250 gb hdd, frontech keyboard and mouse both ps2