How about posting your system specs and your game settings so we can get to the bottom of your problems.
I have my PC overclocked 1.2Ghz TB at 145x10 and am running all the game settings maxed out. And have not had one crash in over 40hrs+ Game play.
What type of RAM do you have? Your type of problem is usually caused by cheap/no name RAM.
So post your specs and we will see if we can better help you
