you can also try removing all the computer parts outside of the case and reseat them over again. reseat your cpu and like the other post said, try testing out the ram. you can download a program called memtest86 in www.majorgeeks.com
and test your ram to see if one of them is flaky. cooling issues could be it also and check your bios temps to see if that is the case.
for system cooling, anything close to 40c is not good. for cpu, hitting close to 60c is not good either. it could also be your videocard drivers and you can try changing them if you havent already. good luck