ALT key always triggered while in-game

Many times as soon as you fire up the game it handles the ALT button like it is always pressed.

I was thinking for a long time why do my game keep minimizing to the desktop when I hit ENTER to chat with somebody. Well, that's the reason: The ALT button is always pressed and threats it like ALT+ENTER which in Windows means toggle full screen on/off.

But I didn't fully figure it out until today when I pressed F4 to change a seat in a vehicle, My game closed completely. 😕