Black at startup in Ubuntu 10.10

[MichaelPalin]

Suddenly, my Ubuntu 10.10 loads invariably to a black screen. It happens both with the normal mode and the recovery mode. After GRUB, a blinking underscore appears for various seconds until it disappears and the screen turns black. In recovery mode, a lot of command lines appear one after another until, as before, the screen turns black. The monitor still seems to receive info from the computer, it does not switches to energy saving mode, but all that can be seen is black.

The last thing I remember doing before this happened was changing the visual aspect of GRUB. I raised the resolution and the color depth, but GRUB seems to work just fine.

Any idea?

Thanks in advance.

[Rubi1200]

Hi,
what graphics card do you have installed?

[MichaelPalin]

HD Radeon 3870X2 with open drivers.

[MichaelPalin]

HD Radeon 3870X2 with open drivers.

[Johannes Eva]

Suddenly, my Ubuntu 10.10 loads invariably to a black screen.

Same problem with Ubuntu 9.10.

Worked for month but suddenly frozen at startup - black screen at login.