after last lock-up, although I could restart kdm, vdpau didn't work until I'd
powered off and restarted the machine (vdpau failed even after a kexec
restart):

Failed to open VDPAU backend libvdpau_nvidia.so: cannot open shared object
file: No such file or directory
[vo/vdpau] Error when calling vdp_device_create_x11: 1
Error opening/initializing the selected video_out (-vo) device.
Video: no video

Ironically I was getting that message, even though I've only had Radeon
hardware in this machine.