This happened to me two times. Working in MS Word, with my laptop on for at least for 2 hours, Ctrl key apparently keep pressed, but phisically the Ctrl key is not pressed. I know about it because when I press programs in the taskbar they don't respond, or when I select a file the mouse select every one of them. I press Ctrl key lots of times to see if it get released, but nothing happens. Sticky keys seemms not to be activated. What can it be?