Not really sure but it would probably help if you could rerun X configuration.
At the LILO/Grub screen, press Ctrl + X or Escape key and login as root.
. When running Xconfigurator you would want to skip X test sequence.
Also make the values of your monitor's Vertical and horizontal freqs ready.
Then reinstall the NVIDIA packages and edit XF86Config-4 as necessary.
Sorry, not much help there..