something went wrong with your install.
do this to correct it:
boot up normally, DO NOT use FAILSAFE or ANY other mode!!! just the normal one.
when it says 'press I to go to interactive mode' press 'I' but do it real fast! It must appear before the next line.
after a while you will be asked to load this or that.
press Y to all, EXCEPT the 'dm' (display manager) after that you can press C. (continue)
log in as root in a text console:
vi /etc/XF86Config-4 (press INS first, change nv to nvidia, then press ESC:wqENTER )
that should make the problem dissappear. if it does not work: post the logfile and config file...
Alien is my name and headbiting is my game.