what game is not playing in full screen? is your laptop crashing or is it just that your desktop crashed?
try to focus on just one issue and describe that more.
-the game title that isn't playing in full screen?
-are other games playing full screen or it just the one?
-have you set the resolution in the game to the correct resolution of your screen?
-is the game playing in windowed mode and just needs to be flagged as full screen?
-are you using a client like steam to launch the game?
any and all info you think may be relevent will help others to give you the best and most accurate advice they can, first you have to help them understand your issue.