Found this. Did you try any of this? I'll bet you did since it's the first thing I came up with.
Quoted from Wikipedia:
Sticky keys is a feature of computer Desktop Environments. It is an accessibility feature to aid users who have physical disabilities. Sticky keys allows the user to press a modifier key, such as Shift, Ctrl, Alt, or the Windows key, and have it remain active until another key is pressed.
On Windows, it is activated by pressing the Shift key 5 times in sequence or by holding down a modifier key for longer than 5 seconds. When sticky keys is activated in Windows, a beep is sounded whenever the Shift, Ctrl, Windows key, or Alt keys are pressed henceforth. It can be disabled by pressing both Shift keys at the same time. Another way to disable it is to press on Ctrl and Shift at the same time, or to hold down the shift key for 5-10 seconds.
On Windows XP, it can be disabled through the Control Panel's Accessibility options. The shortcut used to re-enable it can also be disabled through the StickyKeys Settings found in the same dialog box. However, once Sticky Keys is turned on, it appears that short of rebooting the computer the user has no way to get their keyboard to work regularly again. Or you can just press 2 keys at the same time. Refer to the sticky keys settings.