When booting 13.04 to the 3.5.0 kernel that came with 12.10, the NVidia drivers seem to be playing up. Screen resolution is not what it should be, and I can't set it to the correct resolution either. The "NVidia X server settings" tool gives the following error dialog:
You do not appear to be using the NVIDIA X driver. Please edit your X configuration file (just run
nvidia-xconfigas root), and restart the X server.
However, running nvidia-xconfig as root doesn't fix it. I tried both NVidia's 310 driver (which works on the default kernel) and the 304 driver (which used to work on 3.5, ubuntu 12.10), but no dice. GPU is an NVidia Quadro FX570M.
The reason I'm booting to the old kernel is that I'm encountering what appear to be processor scaling issues with the 3.8 (and 3.9) kernels, which I don't remember from the 3.5 kernel - which is why I want to try it out.
EDIT: The Nouveau driver seems to be having troubles as well now, reverting to 640 x 480 resolution on both the 3.5 and 3.9 kernels. Something's seriously messed up, isn't it?