Known bug #1568604: "Mouse cursor lost when unlocking with Intel graphics"[1]. There are many suspend/resume/power management events which can cause the cursor to disappear. The refrigerator cycling is probably causing a brief power dip or surge which the computer interprets as a power cycling event. There's a fix, and it's gradually going into the various Linux distros.<p>When this happens, try CTRL-ALT-F1 followed by CTRL-ALT-F7. That switches the display to text mode and back. If that restores the cursor, this is the problem.<p>[1] <a href="https://bugs.launchpad.net/ubuntu/+source/xserver-xorg-video-intel/+bug/1568604" rel="nofollow">https://bugs.launchpad.net/ubuntu/+source/xserver-xorg-video...</a>