Samsung Galaxy S6 beeps and goes back and forth between screens

[AC Question]

When I plug my Samsung Galaxy S6 into the USB port on my computer, it starts beeping and flipping between screens. I can't stop it except by unplugging it from the computer. It flips back and forth so fast I can't do anything except unplug it. Help.

 

[B. Diddy]

Welcome to Android Central! Try a different USB cable and/or a different USB port on the computer. Same problem?