I'm finding this First Person view can be buggy... occasionally you get dumped to the desktop if you open a door (right-click) or toggle the crouch (I configured this to either middle mouse button or keyboard 'C', but both had the problem so it isn't the mouse). But I don't have to restart the game... just click the toolbar to bring it back up... but this is a nerve-racking distraction if you're on the verge of discovery by sentries.
I tested this out on two different PCs and it's the same on each, so the instability is in the game when played in First Person... it never happened in the Third Person view
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