I'm happy to see windowed mode is working for you. You should be able to run the game in full screen, there's just something blocking it from doing so.
Just out of curiosity, have you tried lowering your in-game resolution?
Go to Options (...) on the Graphics tab (default tab) To Change the in-game resolution: Go to Screen Size, and from the drop down menu, choose the screen resolution of: 1366x768.
And switch it to full screen in the same tab. To see what happens?
Edited to add:
Hubby mentioned If possible open the case and make sure there's nothing blocking the major air pathways and blow out any dust in there. As it maybe that the video card isn't getting enough air circulation.
MrsFlynn