I'd sooner think you got one very bad mainboard, but wouldn't rule the disk out. I have one Intel Desktop board at
work and it's giving me plenty of issues while trying to install a clean system onto it. It overheats during boot, has
a flaky Intel Pro network card integrated (and I just started to like Intel Pro cards, they seemed good on other boards)
and the BIOS is near useless.
I don't know what model you have, but it sounded very familiar.
If you want a sure check of the harddisk, get Maxtor's PowerMax and boot off of that to check the disk with
a burn-in test. if the drive starts to tick or produce read/write errors, etc. you got a bad disk...
You may even want to test the disk in a different machine to rule out mainboard issues.
Also you can try switching the memory sticks on your mainboard, or try something like memtest on it. I believe
you can find memtest as a boot option on Mandrake Linux' install disk 1, it will do read/write patterns and other
tests to determine whether or not there are bad spots in your RAM.