SMP stability issues

Hi,

For the last couple of months I've been running NetBSD 3.0.1 and 3.1 (sin=
ce yesterday) on an Abit VP6 SMP motherboard with two P3 866's. The syste=
m is mainly used as a mail, web, and Samba server, along with occasional =
other odd tasks.

When I run off the GENERIC kernel, the machine is rock solid stable. Howe=
ver, when I use either GENERIC.MP or my own kernel (which is basically GE=
NERIC.MP with pcmcia and sound support removed), it invariably locks up a=
fter a time running. It is a hard lockup, nothing will revive it other th=
an hitting the reset switch.

The uptime before the lockup has so far varied between about 1 hour and 6=
 days. There doesn't seem to be any pattern to it, other than the fact th=
at it only happens when running an SMP kernel. I can't find anything in t=
he logs to give any clues.

I'm pretty sure it's not a hardware fault, as I've tested everything I ca=
n think of. Added to that, prior to running NetBSD the box ran Linux (in =
SMP mode) without any problems (uptime was 193 days when I took it down t=
o install NetBSD). The root filesystem is on RAIDFrame, if it makes any d=
ifference.

Does anyone have any ideas about what could be causing this, or any troub=
leshooting clues? Needless to say, it's a very irritating problem.

Thanks in advance,
Chris.