Problem solved. I'm still on 2.6.12-rc2, though I suspect this makes no difference. The end solution was to physically reloate the card to a slot where it did not share an IRQ. This is an older motherboard that has some crazy IRQ issues. It would be nice if the driver could spot this situation and complain, rather than silently acting like everything's OK, but the otherwise everything seems to work. Thanks for all the help from everyone. If anyone would like to track things down and fix the driver to either detect the situation or (even better) handle it (if possible) with no problems, I'd be willing to assist with at least testing help (and I do know C and some of the kernel internals).
