I have an HP L2310CU notebook. I've run every diagnostic I could. The entire PC DR suite, memtest86, et cetera. Everything came back just peachy. I physically removed the notebook keyboard. I've used USB keyboards (three different models). I've uninstalled windows, then installed XP, followed by Vista, followed by Ubuntu. No matter what I do, whenever possible the computer just prints a continuous flow of equal signs, as if a key is stuck. Even when no keyboard is present at all.
What is most likely the problem? How can I fix this?