How to diagnose system freezes?

[Dieter BSD]

Adrian writes:
> the "cycle over a short period" may not be the driver writing the same
> crap to the card. I've seen similar failure modes in windows where
> during playback, if the system hangs for whatever reason, the card
> plays the last sample over and over in a loop.

Ok, that makes sense.  So it could be any device driver.

Seems like diagnosing a device driver that is stuck in an
infinite loop (or equivalent) with all interrupts shut off
would be rather difficult.