I installed Karmic 9.10 on a friend's machine a month ago. Everything was working OK (Ubuntu Karmic 9.10).
Since yesterday evening, on booting, he gets the Grub prompt, then the circle, then a blank screen and nothing else.
He can press Ctrl-Alt-Delete to reboot, but the same thing happens every time.
The default kernel shown at the Grub is 2.6.31-16. When he boots with the other alternative, 2.6.31-14, exactly the same thing still happens.