Strange crash: STOP 0xA with instruction address 0.

[Theodore Norvell]

With NT4.0 (Build 1381) SP1 and now SP2, I keep getting a message

STOP 0xA (0x0, 0x2, 0x0, 0x0)
IRQL_NOT_LESS_OR_EQUAL

Can anyone make sense of this? The error code 0xA and the first 0 seem
to indicate it's a null pointer dereference. The final 0 seems to indicate
that the address of the instruction is 0! This can't be right, can it?
All references to STOP 0xA in the microsoft knowledge base web site
have sensible instruction addresses.

I get this error seemingly at random. Often the OS crashes when I'm not
even using it, e.g. overnight. With SP1 it happened about once a day.
I only went to SP2 yesterday, but it had happened again when I came
in this morning.

This system has a Pentium, SCSI and IDE drives, and an ethernet card.
It never crashes when running Linux, but does crash rather a lot with
Windows 3.1.

A related question: What exactly is an internal request level (IRQL)?

Thanks for any help,
Theo Norvell