Bug: unit selection is always on

[the_old_moloko]

So I've been experiencing this random bug that happens late game (usually at the most intense times of a game) where any unit i click (building and units) is selected as if I was holding down the "shift" key. Chat message won't work and all hotkeys are disabled (well not entirely disabled as pressing the g key will take me to the mining camp but without pressing ctrl). If i alt tab out of the game it may fixes it only for a few seconds or a minute.

Is this a bug or am I hitting some combination of keys?! PLEASE help me as it makes the game unplayable once it happens. :(