Nwiz is shipped with Nvidia drivers and loads as a background task by default. Its purpose is to allow the use of multiple monitors with an Nvidia card. Having tested it myself, it seems to run fine with M&B's F2 function.
Judging by what it does, likely suspects would be the graphics drivers or any display related app running at the same time. Check your drivers are up to date, and make sure you have nothing else running which might make use of the display drivers (like nwiz, or those quick settings programs most drivers ship with).
If that doesn't work, then we'll need specs on your system.