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I've tried all the solution I could find on the matter so far, but the error persists. My problem is that the login screen (both under gdm and lightdm) runs with the wrong resolution, even though all is fine when I log in. The error occurs solely when I have my HDMI cable connected to my other screen. The login screen resolution becomes 1024x768 (for my 1366x768 laptop screen) and mirrored on my screen, which is 1920x1080.

I've had this issue on version 12.04 (the last one before I upgraded to 13.04), but I got it fixed by adding the xrandr commands on the begining of the /etc/gdm/Init/Default file. This doesn't seem to work anymore.

I've also tried telling lightdm to run a script fixing the resolution with xrandr (by editing /etc/lightdm/lightdm.conf), but lightdm crashes, and I'm forced to log in with low graphic settigs.

Hint: when ubuntu is loading, the resolution starts OK, then goes bad right before the login screen is initialized. Does that mean that there's nothing wrong with my graphic cards?

What do you think? Cheers!

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I faced the same problem running Ubuntu Gnome 13.04. My laptop uses a ATI Radeon graphics card. The laptop display runs at 1980x1080 resolution and I have a Dell 1980x1200 screen connected through the HDMI port. This morning, I installed the fglrx proprietary display driver and it solved the issue. I get the full resolution login screen now and the laptop has been running 15o cooler since! You may want to try this, and see if it works for you.

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Please add the specific steps to solve the problem. – Braiam Aug 2 '13 at 1:53

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