Problem with FreeBSD (4.9-REL to 5.2.1-REL) on NForce 2

I've got a Shuttle SN45G box that has an NForce 2 chipset that I was having
problems getting working.  Having replaced the faulty memory I'm now left
with a major problem - FreeBSD won't install.

I can install Windows 2000, Windows XP, Mandrake 9.1 and Mandrake 10 without
problems - which is a shame, because I don't want to run any of those :)
However trying to install FreeBSD results in a lockup during the installer.

With 5.2.1-REL it dies at the "Probing devices" message.  When I say "dies",
I mean it - complete lockup - not even the keyboard LEDs will change state.
Doesn't matter if I boot with or without ACPI, into safe mode or what.
4.9-REL has a similar result, except it thrashes the hard disk for 1-2
seconds before it dies.  I've tried leaving it for 5 minutes, but still no
dice.

Now, when I get a chance I'll try a working FreeBSD disk in the box, but
before I do I'd like to know if anybody else out there has it working.  Or,
if there's anything I can do (keeping in mind that I'm not a programmer) to
debug this and help get NForce2 support working (at least on this box).

TIA

-- 
 Rob MacGregor (BOFH) [PGP key ID 0x1E51BF5A]
        If I cannot bend Heaven, I shall move Hell.
                           -- Publius Vergilius Maro (Virgil).