This is a graphics card problem, which is common for Geforce cards. Did you update your graphics drivers recently?

Go to this site, and follow the beginning instructions: https://www.toxik.sk/mayaenv-configuration-of-variables/

Set the following in the maya.env file.

MAYA_SLOW_DRAWPIXELS = 1
MAYA_GEFORCE_SKIP_OVERLAY=1

If this doesn't work, try using an older set of drivers.