[hightreason]

This has always happened in Build games, like if you had the key pressed and something interupted the game (Screensavers used to do it to me in Duke 3d when i didn't use the mouse) the game would not notice that i had let go of the key when i went back to it.

Also i have noticed that sometimes when a Build game is drawing a new area, the keys will sometimes lock like this if the drawing and the keypress/key release coincide at the right time.