I just tried adding "acpi=off" to the grub stanza for the 2.6.15.26 kernel and that seems to be a successful workaround for the problem. I'll post dmesg etc. later in the day when I'm back on that system.
-- VIA IRQ quirk changes in 2.6.15-26.44 have broken various VIA devices https://launchpad.net/bugs/52649 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs