problem installing kubutn 7 on hp nc 8430

[Luca Ferrari]

Hi all,
I cannot install a kubuntu 7.03 from the cd to a compaq nc 8430 with a ati 
mobility radeon x1600. The boot starts but when it's time to switch to X a 
black screen stays there. The system is alive, and I can switch to virtual 
text consoles thru ALT+Fn. The kubuntu 6.1 cd starts well and shows me the 
GUI, so what about the newer version? I've tried to start specifying noacpi 
and nolacpi but nothing changed, and I've also tried to specify a different 
screen resolution.

Any suggestion?

Thanks,
Luca