Right click an empty area of your desktop and choose properties-settings tab, move the sliders to a higher color setting/resolution and click apply and okay out, you may have to reboot (if this works). If not there could be a corrupted display driver.
Can he get to restore or does the start-progs not work? If it does restore the system to an earlier, pre-kaboom date.
He could also check the keyboard to see if any of the keys are stuck. Try swapping the mouse as well.