IRQ problems b/n USB and PCI modem... help!

[Philip Hallstrom]

Hi all -
 	I am in IRQ h*ll.  I'm trying to setup an box to use as an inbound 
modem server...

Here's what's happening...

FreeBSD 4.9
Dell Dimension XPS T450 (ie. several year old dell).
Default BIOS settings (switching the PnP OS has no effect).

One NIC recognized as fxp0.  One IDE drive, one cdrom, one floppy.
Three USR 5610B PCI modems (which work fine individually).

I can access the first two modems via tip, but tipping to the last one 
locks up the entire system (network, console, everything).  Here's the 
relevant parts from /var/run/dmesg.boot:

pci1: <3Dfx Voodoo 3 graphics accelerator> at 0.0 irq 11
ata0: at 0x1f0 irq 14 on atapci0
ata1: at 0x170 irq 15 on atapci0
pci0: <Intel 82371AB/EB (PIIX4) USB controller> at 7.2 irq 9
fxp0: <Intel 82559 Pro/100 Ethernet> port 0x1000-0x103f mem 
0xf4000000-0xf40fffff,0xf4100000-0xf4100fff irq 11 at device 13.0 on pci0
sio0: <3COM PCI FaxModem> port 0x1070-0x1077 irq 10 at device 14.0 on pci0
sio0: moving to sio4
sio4: type 16550A
sio0: <3COM PCI FaxModem> port 0x1078-0x107f irq 7 at device 15.0 on pci0
sio0: moving to sio5
sio5: type 16550A
sio0: <3COM PCI FaxModem> port 0x1080-0x1087 irq 9 at device 16.0 on pci0
sio0: moving to sio6
sio6: type 16550A
fdc0: <NEC 72065B or clone> at port 0x3f0-0x3f5,0x3f7 irq 6 drq 2 on isa0
atkbd0: <AT Keyboard> flags 0x1 irq 1 on atkbdc0
sio0 at port 0x3f8-0x3ff irq 4 flags 0x10 on isa0
sio0: type 16550A


I am pretty sure my problem is that the USB controller and the third modem 
are both using IRQ 9, but I can't think of any way to resolve that.

I don't have USB compiled into my kernel and there aren't any settings in 
the BIOS to shut USB off completely.

I've also tried killing off sio0/IRQ4 in hopes the modem would take that 
IRQ, but no luck there either.



Anyone have any ideas on how I can get this to work?  Should I try FreeBSD 
5.x?

Thanks all!

-philip