did you install the drivers from Nvidia's website?
All you have to do is download the driver package.
from here
If you use the RPM, just install it like you would normally do. Then get into a terminal and run "depmod" and then "modprobe nvnet"
You can also compile it from scratch using the src.rpm file..
If you can't use the RPM for whatever reason or your are distro that's not supported you just have to use the source code "tarball" instead. "tar zxfv nvidia.driver.file.name.tar.gz" and the "cd into.new.nvidia.folder" and then read the README file (very important) and follow it's directions.
Nvidia should have all the directions you need to get their drivers going.
You can check if you already have the nvnet file, buy
cd /lib/modules
du -a | grep nvnet
That will show you the name of the file and it's path. If it's there it may not be for your kernel if you have a upgraded version. You can have more then one kernel, and each kernel will have it's own set of drivers. But you can only use the drivers for the kernel you are currently using.
You can find out which kernel you are currently using, buy using the dmesg command.
dmesg | less
It should be the first line. Dmesg will also show you important information on the hardware that can be detected. You can also find the kernel version by going to the special file /proc/version and reading it.
To uninstall it. Just delete the nvnet.o module file. Or if you are using RPM's then uninstall that specific RPM.
You don't have to uninstall it to reinstall it. The file will simply overwrite the old one. (should)