Interrupt handling problem in WinXP.

Archived from groups: microsoft.public.windowsxp.device_driver.dev (More info?)

Hi, Folks.
My PCI device generate IRQ and everything works while it is enumerated
as "Bus2 Device 0 Function 0".
If it is Bus 2 Device 0 Function 1 (or greater), my driver's IRQ handler
never gain control, system swallows interrupt (and hang as a result).
Do anybody happen to know a workaround?
(Situation is slightly more complex. Details below)
TIA
--------------------------
PCI board contain a P2P transparent bridge (i80152) and two identical
devices on a secondary bus.
One of the on-my-board devices work fine, any IRQ generated by the
second hangs the system.
I've added an instruction to lit the on-board LED as the very first
thing to do in the interrupt handler of my driver
and if system hang the LED is never ON.

*Everything* works on several PC machines.
The problem appear with VIA Epia MS and VIA Epia-M mainboards. All MB
native drivers installed, etc..
(Windows XP pro, my board's driver and client software is exactly the
same)
There - in VIA Epia-xx two other system (on-MB) devices are hooked on
irq10 line: audio and USB.
I've tried disabling both, but it didn't help.
I'm lost. Where to go, please suggest.