Since Ubuntu does not provide a package with the CUDA drivers i had them manually installed.
All things are great till you get a new kernel update from Ubuntu...
After the kernel update the NVIDIA driver (as expected) does not load and your X server switches to a low resolution mode.
Then you need to re-install the NVIDIA CUDA drivers and it can be a bit problematic since the installer requires X server to be shut-down.
So here is what i do
to switch to a terminal window, and login
sudo /etc/init.d/gdm stop
That stops the X server and you can now install the drivers.
Go to the dir where the NVIDIA-Linux-x86_64-XXX.XX-pkg2.run file is
(I am currently using NVIDIA-Linux-x86_64-177.67-pkg2.run) and write
The installer will warn you about an allready installed driver but you can ignore it.
Then it will not find a pre-build module so it will build it on the fly.
When asked about updating your X server config, answer no, as this will probably mess-it up.
Do a reboot and the NVIDA logo (with the big BETA) should come up and you should now be in the same mode as before the kernel update.
BTW you do not need to update the NVIDIA SDK or the tools.