formula400

hello, i got my pc about a week ago and i love it, but i get this problem

i got crysis for it,installed it but after playing the 1st 10 mins it locked up, made a repeted sound and re-started my pc, started it up again and it did the same. that was with all the setting on high, did the same again on medium

my spec is as follows

i had it over clocked by cyberpowersystem, i chose the safe and sable overclocking still with warrenty.

CAS: NZXT HUSH 420W Black Mid-Tower Case
630 power supply
CS_FAN: Default Case Fan
CPU: (Sckt775)Intel® CoreT 2 Duo E8400 @ 3.0GHz 1333FSB 6MB L2 Cache 64-bit overclocked to 3.60
CD: SONY DUAL FORMAT 18X DVD±R/±RW + CD-R/RW DRIVE DUAL LAYER
FAN: CoolerMaster Liquid CPU Cooling System (Superior Cooling Performance + Extreme Silent at 20dBA) [+34]
HDD: Single Hard Drive (320GB SATA-II 3.0Gb/s 16MB Cache 7200RPM HDD
HDD2: 320GB SATA-II 3.0Gb/s 16M Cache 7200RPM Hard Drive [+51]

MOTHERBOARD: MSI P35 Neo-F P35 Chipset LGA775 Supports Core 2 Duo CPU FSB1333 DDR2/800 Mainboard w/GbLAN,USB2.0,&7.1Audio
MEMORY: (Req.DDR2 MainBoard)4GB (2x2GB) PC6400 DDR2/800 Dual Channel Memory (Mushkin Value Select or Major Brand)
NETWORK: ONBOARD 10/100 NETWORK CARD
OS: Microsoft® Windows® XP Home Edition w/ Service Pack 2

SOUND: HIGH DEFINITION ON-BOARD 7.1 AUDIO
VIDEO: NVIDIA GeForce 8800 GT 512MB 16X PCI Express Video Card

what should i do to sort this problem out