Originally Posted by AaronP
The problem appears to be that that particular card isn't responding to requests from the CPU:
I'd suggest re-seating the card to make sure it's firmly in the socket, and thoroughly cleaning all of the heat sinks and fans inside the case.
That's interesting, since I could still get console output from the card.
Nevertheless, I reseated it (and discovered the GPU fan was blocked -- by another fan, amusingly enough), and the kernel module now loads. Thanks!