To reproduce, open ddb(4) using ctrl+alt+esc and type "continue" at the prompt. Typing into the system console afterwards will not do anything. Note: the ctrl and esc keys do not seem to be stuck after exiting ddb(4), it seems to be only the alt key. To confirm this, press ctrl and esc separately after exiting from ddb(4) and notice that the problem does not go away; it goes away once you press alt.