The other half has just upgraded from 10.04 to 12.04. Upgrade seemed to go smoothly but on boot the higher-res splash screen comes up nicely then just black. It's not possible to login blind, which suggests to me that there's no login manager there rather than it being there and being at the wrong resolution or whatever.
If I ssh from my machine I canand up it comes (no error messages or the like) which shows that there's nothing fundamentally wrong with the graphics system - just no login screen on boot.Code:sudo service gdm start
It's moderately old and running some kind of onboard Intel graphics, if that helps. I can list more if it's necessary.