System keeps rebooting with blue error message PLEASE HELP!!!

Hi, i've recently built a pc for a friend and everything seemed find for the first few days,
then the system started reseting itself for no reason at all.  it doesn't seem to matter what
he is doing at the time, whether its sitting idol, browsing the net or playing a game.

Most of the times it resets i get this blue message come up just before it reboots:

A problem has been detected and windows has been shut down to prevent damage to your computer.
I've tried everything i can think of to fix the problem (including reformating about 3 times)
but it just doesn't seem to do any good. If anyone can help me out i would be very thankfull...

PFN_LIST_CORRUPT

If this is the first time you've seen this stop error screen, restart your computer. If this
screen appears again, follow these steps:

Check to make sure any new hardware or software is properly installed. If this is a new istallation,
ask your hardware or software manufacturer for any windows updates you might need.

If problem continues, disable or remove any newly installed hardware or software, disable BIOS
memory options such as caching or shadowing. if you need to use safe mode to remove or disable
components, restart your computer, press F8 to select advanced startup options, and then select
safe mode.

Technical Information

***  STOP:  0x0000004E (0X00000099, 0X0003576D, 0X00000003, 0X00000000)

Begining dump of physical memory
Physical memory dump complete

Contact your system administrator or technical support group for further assistance.

The system includes the following hardware with windows XP pro and service pack 1 & 2 installed:

ASUS P5V-VM DH Socket 775 Core2Duo ready P4M890 onboard 5.1 audo and VGA mATX

Intel Core 2 Duo E6400 (2.13ghz) Socket 775 FSB1066 2MB Cache Retail Boxed

Ebuyer 1GB Kit (2x512MB) DDR2 533MHz PC2-4200 240pin Extra Value Ram

Asus 7600GS SILENT 512MB DDR2 PCI-E

Seagate ST3250620AS 250GB SATAII/300 7200RPM 16MB Cache

Sony AW-G170AB2 18xDVD±RW/RAM Dual Layer Writer Black

Logitech OEM Cordless Desktop Keyboard & Rechargable Mouse Black PS2/USB

SONY DDU1615 16x48x DVD-ROM Internal IDE (Black)

Extra Value ATX Midi Neon Case with 400W PSU

Crap quality power supply could well be the culprit. Try swapping it for sometihng decent like an Antec, Enermax etc or something that is at least £40 worth.Gregoroth

Last time I saw an error like that, it was a memory issue. The RAM could be bad, or not seated properly. If you can, try using a different stick of memory.PikaPichu

you could use a multimeter to test the power supply, or check to see if the correct voltage is getting to the pins on the motherboard

Ok Cheers, is there anyway to test the current power suply for faults etc. before i go out and get another one??? just in case the power suply isn't the problem...Zorg2004