I have just upgraded to Ubuntu 9.10 (network upgrade using the update manager, from 9.04 which had different graphics related problems) and when I try to boot into it all I get a small Ubuntu logo, flickering text and then the tty1 command line with a logon prompt.
startx gives following error:
Fatal server error: no screens found
I traced down a tutorial that said I needed the latest graphics drivers (Gigabyte ATI Radeon 4650 HD installed with 9.10 catalyst drivers) so I did using the 'sh' command and a USB stick (I have a working Windows partition) and it installed fine but did not fix the problem.
Edit: Thanks to UK and Arjan below I was able to understand the full error message of start x:
Parse error on lone 2 of /etc/X11/xorg.conf 'nameserver' is not a valid keyword in this section Fatal server error: no screens found
This has nothing to do with a graphical error (sorry if I misled anyone) but the xorg.conf file has 3 lines in it and lines 2-3 have an entry 'nameserver'. Using the nano command I commented out (using a # before the entries) the nameservers and can now boot Ubuntu.
Thanks to everyone for their help.