Hi.
It is useful to take a look on the known bugs web page:
http://fedoraproject.org/wiki/Bugs/Common
It advises not to use NVidia driver.
It also warns about some bugs related with NVidia graphic adapters and 3D features, that probably will be corrected in future.
I could solve the error "Fatal server error: no screens found" by adding the following parameter to the kernel when booting from GRUB:
nomodeset
Hope it's useful.
Regards.