Okay, I just bought a new computer: Power Supply ( Standard Case Power Supply ) Processor ( [939-pin] AMD® Athlon-64 3000+ CPU w/ Hyper Transport Technology ) Processor Cooling ( Certified CPU Fan and Heatsink ) Motherboard ( eVGA nForce-4 SLI Chipset Dual DDR w/7.1 Sound, Gb LAN, S-ATA Raid, USB 2.0, IEEE 1394, Dual PCI-E MB ) Memory ( 1024 MB [512MB X2] DDR-400 PC3200 Memory Module Corsair-Value or Major Brand ) Video Card ( [PCI-Express 16x] Nvidia Geforce 6200 with TurboCache Supporting 256MB w/DVI + TV Out Video ) Hard Drive ( 80 GB HARD DRIVE 80 GB 7200 RPM Ultra ATA-100 Hard Drive ) CD-RW/DVD-RW Drive ( [** Special !!! ***] 16X Dual Format/Double Layer DVD±R/±RW + CD-R/RW Drive Black ) Sound Card ( 3D Premium Surround Sound Onboard ) Speaker System ( 600W PMPO 3 PCS Super Bass Subwoofer Speaker System ) Network Card ( Onboard LAN Network (Gb or 10/100) ) Monitor ( LCD Monitor ViewSonic 17" Q7B TFT LCD Monitor [Black] ) USB 2.0 Accessories ( Build-in USB 2.0 Ports ) Flash Media Reader/Writer ( 12-In-1 Internal Flash Media Card Reader/Writer Black ) Operation System ( MS Windows XP Home Edition w/Service Pack-2 ) Anyhow, I get on the computer and install steam. It worked fine, then I installed Halflife 2 from my account. That work, so I rebooted just-in-case, and ran halflife 2 from the steam games list. Suddenly, my moniter changes turns off and says "no signal input" and then my whole computer restarts. I have the latest nvidia drivers and I've reinstalled steam and halflife 2 about 3 or four times. If anyone can help, please do. Thanks.