sudo apt-get install xscreensaver
sudo reboot

The above fixed my issue.

Hello,
I installed the magic mirror and have the program autostarting. Around 20 minutes, the screen goes to blank. If I plug in a keyboard, hit F11, it will minimize the magic mirror window and refresh it. If i it F11 again it will maximize the window and continue on until it goes blank after another 20 minutes. Does not seem like the Pi or Monitor is asleep or screensaving as hitting F11 causing a very fast automatic minimize and refresh. Any advice to stop this?

Thank you,
Craig