Check all of your keybinds and make sure there are no accidental mistypings for the keybinds. There may also be background programs, for me it's the security update that happens at 7:00 am and pm, that switch to the desktop just to annoy the forget out of you. The next time this happens, and if it is not a Blockland issue, open the Windows console and check for anything that doesn't look like blockland before the whole desktop rendering lines.