Yeah, I've seen that funky message. It usually means that the serial driver tried to talk to /dev/ttyS1 and it basically couldn't probably because it wasn't guessing right about the IRQ or base address. After running "modprobe isa-pnp," what do you get for the base address of the modem as detected? I have also seen that message when the driver tried to talk to my PCI modem. I had to forcibly enable the PCI modem with both Redhat and Slackware.
