Computer beep then freeze after 2-3 hours and upon shutdown?

[Sowers]

Having some problems with my new build any help is greatly appreciated.

I get this really long BEEP constant whenever I am on my computer an extended amount of time (2-3 hours) then it will cut off by itself. Also when I shut down the computer it will do the beep sometimes and hang also and I have to shut down using the front power button by holding it down.

Specs are:
E6600
asus p5b
geforce8800 gtx
2 x Corsair xms DDR2 Ram
seagate 7200 rpm.

 

[cutthroat]

Sounds like overheating, what are your temps?

 

[Sowers]

CPU stays around 42-45 C and MB at about 33-34C