The kernel interface layer of the NVIDIA kernel module must be
compiled specifically for the configuration and version of your kernel.
If you upgrade your kernel, then the simplest solution is to reinstall
the driver.
ADVANCED: You can install the NVIDIA kernel module for a non
running kernel (for example: in the situation where you just built
and installed a new kernel, but have not rebooted yet) with a command
line such as this:
sh NVIDIA-Linux-x86-1.0-6629-pkg1.run --kernel-name='KERNEL_NAME'
Where 'KERNEL_NAME' is what `uname -r` would report if the target
kernel were running.