powerbook: wrong image displayed in external screen

[Julio Herrero]

Hi!

If I connect an external monitor via the DVI connector, the monitor
image appears divided into randomly displayed squares... the effect is
the same if I change the resolution of the powerbook screen.

The incredible thing is that the mouse cursor is neatly drawn...

The graphics card is an ATI Radeon mobility 9600.

Any hint, please?

Thanks

Julio