Minecraft controls messed up / not working!!?

About 2 weeks ago, my sister's Minecraft game on her computer was messing up. Whenever she tried to use WASD or open her inventory, it would just scroll to a random spot in the hot bar (1-9). When I try to change the controls in the options menu WASD shows up as a random number every time I try to change the key. I have found that many people are having the same problem on numerous sites (Google: Minecraft controls not working). I have tried to re-download the minecraft game (Launcher and Appdata folder). I have re-installed my keyboard drivers, and even went as far as re-installing my computers OS (wiping all data). The game still doesn't work. My sister's computer is running Windows XP on a 4 year old computer.