Intel Core 2 Duo, Gigabyte mobo, I-Box AC, ATA hard disk fails to boot with IDE/BIOS errors

I am trying to diagnose a hardware malfunction

Specs:

• Intel Core 2 Duo, 3 GHz
• Gigabyte Motherboard
• I-Box AC, 400 W
• ATA hard disk
• 4GB RAM (2 x 2GB)

1. First boot, passed POST Check, went to IDE detection, than froze.
2. Second boot, entered BIOS, not responded to keyboard input, froze.
3. Third boot, launch OS (WinXP) from it's hard drive, spit a lot of error of files corruption ("Explorer.exe - file corrupted" in Polish), but worked pretty stable.
4. Fourth boot, entered BIOS, allowed to change boot device priority.
5. Fifth boot, boot-in Linux (Ubuntu) from CD-drive, unable to detect LAN card, but mounted hard disc and accessed filesystem - I've made backup of all files.
6. Sixth boot, boot-in memtest 86+, run for 12 hours (19 pass, no errors).
7. Next few boots, unable to pass IDE detection (freezes).

I am out of ideas. It's almost sure for me it's motherboard failure, but I don't know if there is something else I may search for. Is there anything I can do beside motherboard replace?

I loaded failsafe BIOS settings as suggested by one of answers and surprisingly this fixed booting problems or at least for now (I've made 5 clear boots without errors so far). I run chkdsk on all drives and it found several errors on system drive (mostly wrong file indices), but no bad sectors. I also ran a Kaspersky 10 antivirus bootable CD and it found 1 Java exploit, but nothing more serious. Now Windows is popping "Exception Processing Message 0x000000a3 Drive not ready" error boxes at random during normal work, but otherwise is pretty stable. I caught one system reboot - after which I set to not automatically reboot after BSOD, but no more BSODs actually happen

Just thoughts really:

Can you flash the BIOS? It could be the motherboard but I just doubt it because you got error messages that the OS was corrupt (explorer) - I would suggest the basic things first - check to ensure all cables are plugged in and that it's free of dust in all vents.

Change the IDE cable.

From within the BIOS load Default Settings.

When PC boots, press F7 to run last known good configuration (if you can get that far).