I'd think this is a hardware problem. Some things that have caused me
similar grief in the past:
It is possible, but I can rule most of them out. I think it's unlikely.
Bad IDE cable
Bad SATA cable
Ruled out. Only SATA drives. I used two different HDs (separatedly) with
different cables, and the live CD. It's not the cables or the drives.
Bad power supply
Bad motherboard
Both are brand new, but of course that doesn't rule them out.
Regarding the PS, I have checked voltages with a multimeter and they are
more than fine, and the wattage is enough for the system, so it'd have
to be a very weird transient glitch that affects only memory access. See
also below.
Any ideas to rule the MB out, other than "get a new one"?
Bad memory (memtest doesn't necessarily access things the same way as
the kernel)
Ruled out. I replaced with a 2GB DDR2, still got the bug: "BUG: Bad page
map in process".
Bad cards (pci, agp, whatever)
Ruled out. The only card is the video card. I replaced it with a very
old PCI board and still got error. This also pretty much rules out that
the PS is underpowered, since I powered only the MB and the HD.
Could it be one of the onboard things? I disabled everything but the
LAN, and still got it.
Any of the above with loose connections
I already reconnected everything twice. Could still be a loose
connection of one of the wires in the connector, but it's very very
unlikely to give such a specific error on memory access.
And did I mention bad power supply?
Yes you did, and I'll try to get another one to be sure, but it could
still be a software bug too.
I tried to install an old Win2K I had here. It doesn't handle the big HD
well and ends up not booting after installation (it can't partition it,
also), but it didn't freeze (even though it formatted the disk and
copied the files, which was not slow). So +1 to being a kernel bug.
The most common error message I get is: "BUG: unable to handle kernel
NULL pointer dereference."