Hey, i think im having a similar problem, and i was hoping that you might be able to assit me. I know this thread was started by someone else but my problem is very similar and i thought it best to include it into the same one.
I recently installed an nvidia kernel module for my fedora core 4 distro. The current kernal that im using is 2.6.15-1.1830_fc4
Before i had this installed everything was starting up fine, the only thing that i did notice that seemed weired is that when my systme was starting up and going through the check list it would always say that nvidia kernel module failed. And i thought this might hinder the rendering of graphic applications so i saught out to fix it and installed the new nvidia kernel.
So now when i start up my distro, the check list is all green, and it even shows this huge logo "NVIDIA" and it even shows my custome sign in screen, but the thing is is that i cant sign in anymore. It seems like my sign in screen is hanging. I can move my mouse but i cant type anything in the box for user name and password.
I was thinking that it probably acting like this because my startup screen is custome. And maybe if it was the default sign in screen i wouldn't have this problem. SO i figured if i could figure out how to reset the start up screen i might fix my problem. And if not that i would like to just uninstall the nvidia kernel module all together. Any help at all is welcome and again im sorry for intruding/