Well, I recently installed slackware 10.0 (it's a "virgin" install, haven't messed with anything, and YES I installed the source) and thought I'd give the nvidia drivers another chance. I GET THE SAME ERRORS! the module compiles but won't load. I found something in the README this time which looked useful:
"Q: I cannot build the NVIDIA kernel module, or I can build the NVIDIA
kernel module, but modprobe/insmod fails to load the module into
my kernel. What is wrong?
A: These problems are generally caused by the build using the wrong kernel
header files (ie header files for a different kernel version than
the one you are running). The convention used to be that kernel
header files should be stored in "/usr/include/linux/", but that
is deprecated in favor of "/lib/modules/`uname -r`/build/include".
The nvidia-installer should be able to determine the location on your
system; however, if you encounter a problem you can force the build
to use certain header files by using the --kernel-include-dir option.
Obviously, for this to work, you need the appropriate kernel header
files installed on your system. Consult the documentation that came
with your distribution; some distributions do not install the kernel
header files by default, or they install headers that do not coincide
properly with the kernel you are running."
So I tried it. It turns out that with the 6111 installer, the --kernel-include-dir option does not exist, and the --kernel-include-path (which was my next best guess as the next closest option) has been deprecated to --kernel-source-path ("for kernel 2.6 compatibility", whatever...). When I tried using this option, I couldn't even get the installer to compile the module, unless I used the proper path to the kernel source (which the installer was using all along), and then when I did, I got the exact same problems as before.
So it seems to me that the documents are a bit out of date, hmmm?
well, I'm this close to taking my nvidia back to the store, and pluggin the ol' Radeon back in. It never worked well, but at least it worked.
failing a fix to this problem (although it needs fixing) I'd be willing to try to install a slightly older version of the driver. Does anyone know where I can get an older GeForce Driver? What would I be missing by not using the latest version?