pcmcia modem

I am running an up-to-date installation of hoary, the modem in question is a
USRobotics XJ1336. It is a hardware modem and I have used it with linux for many
years.

When I insert the modem it is correctly identified and assigned a ttyS device
and an interrupt, but when I attempt to use it (either by configuring the modem
with network-admin or by running minicom) I get a string of kernel errors (see
/var/log/messages listing below).

Jul 18 18:39:31 astoroth kernel: cs: memory probe 0xa0000000-0xa0ffffff: clean.
Jul 18 18:39:31 astoroth kernel: ttyS5 at I/O 0x2f8 (irq = 3) is a 16550A
Jul 18 18:40:05 astoroth kernel: [__report_bad_irq+49/119]
__report_bad_irq+0x31/0x77
Jul 18 18:40:05 astoroth kernel: [note_interrupt+117/155] note_interrupt+0x75/0x9b
Jul 18 18:40:05 astoroth kernel: [__do_IRQ+211/273] __do_IRQ+0xd3/0x111
Jul 18 18:40:05 astoroth kernel: [do_IRQ+25/36] do_IRQ+0x19/0x24
Jul 18 18:40:05 astoroth kernel: [common_interrupt+26/32]
common_interrupt+0x1a/0x20
Jul 18 18:40:05 astoroth kernel: [handle_IRQ_event+26/76]
handle_IRQ_event+0x1a/0x4c
Jul 18 18:40:05 astoroth kernel: [__do_IRQ+190/273] __do_IRQ+0xbe/0x111
Jul 18 18:40:05 astoroth kernel: [do_IRQ+25/36] do_IRQ+0x19/0x24
Jul 18 18:40:05 astoroth kernel: [common_interrupt+26/32]
common_interrupt+0x1a/0x20
Jul 18 18:40:05 astoroth kernel: [__do_softirq+44/121] __do_softirq+0x2c/0x79
Jul 18 18:40:05 astoroth kernel: [do_softirq+34/38] do_softirq+0x22/0x26
Jul 18 18:40:05 astoroth kernel: [irq_exit+41/52] irq_exit+0x29/0x34
Jul 18 18:40:05 astoroth kernel: [do_IRQ+30/36] do_IRQ+0x1e/0x24
...

I don't know if this is a problem in pcmcia_cs or the kernel or something else
entirely.