Hard locks under high interrupt load?

[Dan Creswell <dan@dcrdev.demon.co.uk>]

I'm having zero success in getting 2.6.3 stable under interrupt load.  I 
can kill my machine in a variety of fashions all of which appear, to my 
naive eye, related to interrupt load:

(1)   LAN traffic via E1000 card (X is not running)
(2)   Running X for more than a few minutes - starting up a couple of 
applications whilst performing some disk-based activity (such as a 
compile) usually seems to do the trick.

(2) is worth a little more examination.  I have an NVIDIA card (I can 
hear you all groan) *but* I get the same results with the XFree driver 
*or* the proprietary NVIDIA driver.

Disabling IO-APIC usage seems to resolve the problem.

Machine is a dual Xeon, Tyan S2665 (E7505 chipset) with an MPT-Fusion 
SCSI controller.

2.4.26-pre1 and various other 2.4 kernels give me no problems at all.  I 
really want to switch my machines over to 2.6 but I can't whilst this 
problem persists.

Cheers,

Dan.