I'm having the same problem. However, if I wait 4 minutes (I mean, really f-o-u-r minutes), then I get nVidia splash and everything seems to work fine (but I have not checked the frame rate -I don't know how to do it, and what is the benchmark rate I should find).
I have run the nv_check.sh script (see nVidia site); all is fine but the kernel; it does not find it. But here is another trick: nv_check greps for NVIDIA while in the kernel there is the module nvidia (lower case); furthermore, it is mentioned very often NVDriver, which adds confusion to the right name it should be used.
Anybody can help?