On shutdown computer will always reboot

[kwhubby]

HI, I have a computer I just built with an abit AW8-Max board which I am unable to turn off without forcing it off (either holding the power button or unplugging/switching). As I engage shutdown in windows xp, it shuts down. The computer successfully shuts down but then 1 or 2 seconds later it turns on again.
This motherboard has a post code 2 digit LED display thing on it that tells me what it is doing, the codes are all listed in the manual of the motherboard. As I shut down the computer the post code displays FF (Boot attempt INT 19h) while normally on until finally 98 (De-Assert ATX power supply) quickly and holds at 99 (complete power off sequence), then after about 1 or 2 seconds the post code goes to 83 (ATX power supply ready) and all the computer fans start up as the computer turns back on. Normally the code displays 00 when the computer is off. I put a voltmeter up to the little green ATX psu startup wire and it appears that the motherboard is what is malfunctioning in some way-by re closing the start psu circuit after it shuts down. I have updated the Bios, and removed all peripherals and headers but this didn't change anything.
The full specification of the computer minus drives:
psu: Thermaltake TR2 W0070 430W
ram: corsair value select ddr2 677
cpu: p4 640 3.2ghz 800fsb 2meg l2
graphics: ati x600pro all in wonder


Does anybody have any suggestions, solutions, or comments for my problem?
Thanks!

[oracleguy]

I've never heard of someone having that particular problem before. However if I had to guess, I'd say that the motherboard is defective (as you probably already guessed) if this is a new system, I'd take the motherboard back and exchange it for a new one.

[kwhubby]

Thanks oracleguy for replying. I was able to get it working properly by taking out the little button battery and setting the clear cmos pin. I don't know why it was doing that but I know its working now.

[oracleguy]

Hmm I guess as long as it works its okay but that still isn't normal. That battery is used to keep the CMOS powered which stores the settings for the BIOS. The system will obviously boot without it but it will just restore the (failsafe) defaults on each boot.

I'd still recommend trying to get the board replaced on the basis that if it has one problem now, it could develop more in the future.

[kwhubby]

Well I wasn't clear, I took it out and placed it back in before booting. The computer seems to be working fine after setting all the settings as I wanted it in the bios. If this problem happens again randomly I may consider sending the motherboard back in (or just reset the cmos again) but for now everything seems to be ok.