Pc freezes with long beep im desperate here..

i have bought this new pc recently it keeps on freezing
while playing games..it has happened 7-8 times in the past 3 days. the last time it hanged with a continious beep tone form the motherboard speaker until i pushed the restart button.and once it hangs then it almost becomes regular.
as it happens irregularly i cant make the guys at the pc shops believe my complain.they think im a noob or something..im tired of them..im desperate here..i have spent a lot of money in it.



my specs are..
Windows XP SP-3
MOBO- asus p5Qc
CPU- Q9550 2.8ghz
Ram- DDR3 2X2gbs 1333bus
Harddisk- samsung 160 gb
GPU- XFX GTX 260
PSU- 600w thermaltake toughpower.

ya ... all of them were done in the pc shop.

Is there a time thing in here...... Next time it does it restart and enter bios check your cpu temp. You could run Dr. Watson but thats desprate. We really need more info. Can you turn it on riht after. Is anything OC. F8 Disable auto restart and hope for a blue screen. Hell it could even be a thread getting stuck in one of your perferals.