I bought lasr week a 450 GTS to replace my 7200 GS, and I never made it work.
There was no problems at all with the 7200GS. The 450 GTS works great on my Windows XP sessions.
After the splash screen, it gives a blank screen, and the keyboard don't respond anymore, so no tty1 to analyse the problem. I got the Xorg.0.log in rebooting just afterward in recovery mode and asking telinit 1.
On the Ubuntu forums
, we thought it were a problem with my monitor which seems to have errors with the EDID. So my current xorg.conf is really detailed about my monitor to prevent those EDID warnings.
Anyway, it seems there should be others messages in the Xorg.0.log after the mode selection, and I didn't get any.
The behaviour is exactly the same with both X drivers 270.41.03 and 260.19.44
I generated the nvidia-bug-report while 270.41.03 was installed but not xorg.conf was set so I could start a session normally with the nv drivers.