ACPI problem on linux-image-2.6.32-trunk-amd64 powering off

[campbell mcleay <campbell.mcleay@googlemail.com>]

Hi,

I am running 64-bit Debian Squeeze with kernel
linux-image-2.6.32-trunk-vserver-amd64, and when
I initiate a shutdown to halt/poweroff the system, either within a
Gnome session or on the console,
it reboots instead of powering off. I can see what looks like a kernel
oops error message at the
very end of the shutdown process, and then it reboots (it is too quick
for me to see the exact error).
My suspicion was that ACPI was the issue, so I disabled it at boot
with 'acpi=off', and indeed it no longer
reboots when I issue shutdown to halt it, but I lose hyperthreading
and it won't power off at all. I have
used Ubuntu 9.04 and 10.04 (which uses 2.6.32 kernel) to test the
hardware as well, and these shut
the machine down with no issue. I would use another linux-image
package, but there seems to be only
one for Squeeze (aside from a vserver image).

Any suggestions on a way round this? I don't want to boot with
'acpi=off', as it won't shutdown and
hyperthreading won't work.

Hardware is dual Xeon x5550 with 6GB ram and SSD hard disk.

Cheers,

Campbell