FreeBSD 8.0 suddenly freezing

[Dieter BSD]

> In the last 72 hours, we've had two different systems freeze; they don't
> apparently recognize any interrupts, they won't respond to ping, and
> they require a powercycle to reboot. We can't easily generate an NMI on
> these boxes.

> Just on the off chance, does this sound like a familiar -- and
> preferably soluble -- problem?

Only theory I can think of is that some device driver shuts off
all interrupts and then goes into an infinite loop.

I have had trouble with at least four different device drivers
locking everything out long enough to lose incoming data.
Usually it recovers without a reboot. Not an infinte loop, just
way way too long to leave interrupts shut off.

See also the "How to diagnose system freezes?" thread from July-August.
Yuri found that a particular rev of the nvidia driver went into
an infinite loop.