Today I installed an Nvidia GT440 on my computer, changing the one that existed there, an Nvidia 9500GT. After changing it I started getting a problem where the screen just went black when loading the lightdm login screen (Where I punt my user and password). The thing is, if I disconnect the VGA cable and connect it again I get to see the lightdm greeter and everything works perfect.

The problem is that I have to connect/disconnect every time I reboot the PC.

I tried installing the 285.xx drivers. Same problem. I removed the Nvidia drivers installed with Jockey, rebooted, same problem. I install the current 280.xx again, same problem.

After all that I installed a fresh install of Ubuntu, selected to install the Nvidia drivers while installing it from the livecd. After booting the same problem appeared.

Dmesg does not say anything wrong about it. Same goes for the log from Jockey.

What else should I check or what to do to solve it.

Just to clarify, this does not happen BEFORE the lightdm greeter appears. Am guessing before the actual use of the video card with X starts with all the 2D/3D stuff that is used in ligthdm and unity. I can use any tty and even see the Ubuntu logo when starting.

UPDATE: When I open a game in fullscreen the problem appears again. I have to unplug the monitor cable and plug it back in to see the game. Then when I quit the game I have to do it again to see the desktop.

UPDATE 2: Today I bought a HDMI cable, connected the video card to the TV am testing it with and it actually did log in correctly without any black screen but it shows the resolution a little over the actual size of the screen. So I see only half of the launcher since the left side of it is hidden outside of the real resolution and the top bar is beyond the resolution. So the black screen is related to the VGA connection.