Ok, here's the full story:
I just bought a KT-3Ultra & paired it with a XP1800+, 256mb Nanya DDR + 256mb Hyundai DDR, SPI 300w PSU & Ati Radeon 8500 gfx card. It was to upgrade a pc with win98se installed.
Once I installed all the hardware, I then upgraded 98se to winxp pro straight away. The thing booted normally & functions smoothly, but whenever I shutdown windows, the thing just reboots & goes back to windows. This happens most of the time & only rarely does it powers down as it should. Once or twice it beeps 3 long beeps repeatedly after shutting down windows (it doesn't power down, but the screen is blank & the HDD lamp is on for a few seconds). Whenever it beeps, it doesn't reboot but doesn't power down either. I tried removing the Hyundai ram but same problem.
Then, I updated the bios to ver 5.2, & with conservative ram settings (normal timing & SPD everything), it behaved as it should. I repeatedly shutting it down (abt 7 times) & everytime it worked, powering down normally each time. I had already reinstalled the Hyundai ram this time. Then I upped the ram timing to fast, & it still shuts down windows & powers down ok (I tested it once). All seems well, but then I started up the system, ran it for abt an hour (benchmarking, surfing net), then the old disease came back!! Windows shuts down but doesn't power down the pc, it also beeps 3 long beeps repeatedly again. I then changed the ram timing back to normal but again it does the same thing.
What's wrong? It beeps 3 long beeps repeatedly, & the Dled in the D-bracket has 3 red lamps on & 1 green lamp (green on led #2). Problem with mobo or ram?
Just to add that I have a 3com 3c905b lan card & I think there's no WOL. Also, all ACPI & other bios settings are at default.