I have an issue with my keyboard where the down arrow stops working after around 30-45 minutes of use. I then have to uninstall and re-install the PS2 keyboard driver and then restart my laptop. The down arrow then works again, but then stops again under an hours later.
Well first, you should be uninstalling it, then rebooting and letting the computer reinstall it on its own. Instead of uninstalling it, reinstalling it yourself and then rebooting. Try that and see if you get better results.