Rarely, the controls lock up for about 30 seconds. When a lockup happens, whatever keys I'm pressing stay pressed to the client, and whatever keys are unpressed stay unpressed.

For example, if I'm holding W and looking straight up and a lockout happens, I will be walking forward and looking straight up for 30 seconds, and there is nothing I can do about that except by doing a force quit on Minecraft or waiting for the lockout to expire.

If I switch desktops, that pauses Minecraft, but then I cannot click any buttons or un-pause until the lockout expires.

It is not an issue with my keyboard/mouse because I have replicated this with numerous keyboards and mice.