Hello everyone!
 
Just installed a GeForce 9600GT into my system, and it's causing the monitor to turn itself off, and then the PC freezes.  We need to do a hard reboot.  It only occurs when my son is on-line gaming.  We never had this problem with previous Asus card.
 
Here's what we have:
 
Power supply: 650w by BFG
Sceptre X9W monitor
XP Media Center SP2
Intel Core 2 CPU 6400, 2.13 gHz
3.2 RAM
 
I did some research yesterday and was advised to:
 
--set BIOS display to PCI and disable onboard video (couldn't find it in my BIOS options)
--turn off Enable Write Combining
 
And other thoughts or help?
 
Thanks!  Keith

pci-e 2.0 cards do not work well with all old mobo's  
 
check your mobo to see if they work with pci-e 2 or if you need a bios upgrade
note: usually you get no display at all, not a crash
 
i would check microsoft updates let it scan it may be a os issue with the pci-e 2.0 card

What are the specs of the PSU?

Psu spec- 650 Watt Atx 12 V 2.0/EPS 12V.
 
And your right Dragonspray, the monitor goes blank. We will look to do bios update.

Thanks for your help guys!  
Heres what we have done:
BIOS update for our Biostar T-Force 945-P
Installed new 650 Watt power  
Used a driver cleaner to get rid of old Nvidia drivers
 
Monitor still freezes, followed by the computer freezing, requiring a reboot.
This only happens on FPS games such as Counter-Strike and Bf2. But it will not freeze on the RTS games such as Company of Heroes.  
 
Any more ideas would be appreciated.
Thanks!  
Keith