I've had this error happen a few times. It was caused by a call to set_mode on a display that was already set to another mode. Follow these steps to fix it: 1) Close all programs that are using Python and Pygame. 2) Bring up a command prompt (Start -> Run -> cmd or Windows key + R -> cmd). 3) cd to the folder with your Python file. 4) Run one of the following commands for whichever mode you are trying to change to: >pygame.display.set_mode((800,600)) >pygame.display.set_mode(800,600) >pygame.display.set_mode(800 600) In my case it was 800x600, but in step 3 I had to type out the mode name. 5) Open the .py file, and run it through Python. It should run fine, and there should be no error related to setting the display mode.