I have a similar problem.
However the difference is I have tried the new kernels (currently on 2.6.16-2070) with appropriate .src.rpm and kernel-devel installed. The nvnet ethernet driver installs without problems. But the nvidia audio driver fails to install giving the same error as above.
I imagine this must be losely related to the problems encountered with the nvidia gfx driver and fc5. But what the solution is I don't know.
I hope we can find some answers, and keep this thread alive as it always seems that the nforce drivers are eclipsed by the problems with the gfx driver.
Attached log for more info.
Also I am not running selinux so that should not be causing the problem. *should not*