I have a machine with a Nvidia 8600GT graphics card and a CRT monitor. Previously, I have only used Windows on it, and the graphics card seems to be working correctly in Windows 7. I booted up and installed Ubuntu 11.10 amd64 from the LiveCD and the whole process worked perfectly. When I tried to boot off the hard disk for the first time, the output to the monitor switched off during the splash screen, and this happens consistently. I can ctrl-alt-f2, so I tried an apt-get upgrade, which didn't help; nor did apt-get install nvidia-current. There is nothing that looks relevant in dmesg. Booting with the nomodeset option has no effect.

Following the answers in this similar thread, I tried apt-get purge nvidia-173. Both startx and service lightdm start just say the service is already running.

Does anyone know how to find out what the problem is? I was wondering if it is just that Ubuntu is trying to use a resolution that the monitor doesn't support, but I can't find out how to change that from the command line.