I don’t have a solution, but I can tell you I ran into the same issue with an Acer Aspire 5610Z and the Ath5k driver after applying patches from the latest Online Update and a reboot. When I regress back to the base 11.2 install, my wireless interface works - I’m using it to send this reply.
I don’t have the exact error, but I do notice an IRQ/PCI conflict reported during the boot sequence when I apply the latest kernel and driver.