If you use an external additional display you may encounter this frustrating problem: screen seems to go wider than the display with menus on the dges half-obscured; images are distorted (squashed) and fuzzy; everything seems out of proportion.
Restarting the machine or calibrating the display may not resolve the issue.
One simple trick not to be forgotten is resetting the display. Disconnect (unplug) it from the computer, wait for about 30 seconds and reconnect. The display comes back to its usual behaviour.
It worked for me a few times, so I thought I should share it.