It has happened occasionally that after holding the shift key down for some time (while thinking about what I was going to TYPE), I SAW a dialog box related to holding down the shift key, and then, after clicking Cancel, could not type in any window, and had to reboot. I'm guessing there's a key sequence to undo this (Shift F3 didn't work). If so, does anyone know what it is? I did find the following on the Internet (after I posted this topic):

Disable StickyKeys by pressing both "Shift" keys at the same time. Another way to disable it is to press the "Ctrl" and "Shift" keys simultaneously.

Read more: http://www.ehow.com/how_4822850_undo-sticky-keys.html#ixzz31FGrhjVEIs this a USB or PS2 keyboard? I have seen some USB keyboards act up after a key was held in too long. Replacing the keyboard with a different model fixed it. Had this happen a while ago with gaming and holding down CTRL key to speak through ventrilo. The keyboard would EVENTUALLY become unresponsive. And to get it back I had to unplug the USB cable while system was running and plug the USB cable back in as the temp fix. But when replacing the cheap USB keyboard the PROBLEM was gone for GOOD.