Why can't I play computer games in full screen?

Why does my computer crash while playing games?

• i have a windows 7 home premium my processer is a AMD turion 2 duel-core mobile m500 2.20 GHz i have 4.00 gb of ram .3.75 usable its a 64-bit so heres the story i play games Alot of games so when i find a new game i wanna try it so i bought minecraft and for some reason while i play the game the screen stops turns to a blank screen and i cant do anything but restart the whole thing and it does this while i play call of duty world at war but this computer can handle plants vs zombies but cant handle minecraft also on cod waw it crashes after 15 or 20 mins of playing

• Answer:

  Minecraft uses a lot of memory. NEVER EVER run another game such as COD (It uses even more free memory) while playing MC. It crashes because you run out of free memory so close all background programs and games if you want to play MC. If you run out of free memory MC can't function properly so it will "suicide" itself to give you more free memory. MC is quite kind to other games really!