Abstract: When in System > Preferences > Screen Resolution, if you change the refresh rate and you monitor goes blank, reboot into the terminal, then from your home directory remove the file .config/monitors.xml

This week I was playing around with different desktop wallpapers for Ubuntu and wandered off into the screen resolution settings for gnome. Now, it has been a while since I configured my current monitor, so when I saw I had options for a faster refresh rate I just had to modify it, even though I should have known my monitor didn't support higher rates. I increased the refresh rate and my monitor immediately went blank, then displayed the message "Mode not supported". I patiently waited a couple minutes to see if Ubuntu would automatically revert the settings, but nothing happened. I rebooted the system.

I figured I would have to manually edit the xorg.conf file, something I've done before and have no problem doing. But to my surprise the login splash screen displayed. I logged in and the screen went blank with the same message blinking.

Evidently it must be some gnome user configuration rather than an xorg.conf problem since it happens only after logging in. From another computer I googled for answers, but none seemed to address my particular problem; most dealt with xorg configurations. Then I found a post stating gnome stores settings files in a series of .gnome directories, and removing these files would change my desktop setting back to default.

After booting into a terminal, I searched the files in those directories but none seemed to deal with monitor configurations. Desperate, I deleted them all. I went to log in again but the screen turned blank once again.

To solve this problem, I knew I had to find the configuration file that gnome modifies when configuring the monitor. I created a new user and logged in and opened Monitor Resolutions window. I changed the resolution this time, and saved the settings.

To find files that were recently modified, from your home directory type the command ls -atu | less, which list all files and directories and sorts by time last modified. If you were following my steps, you should notice that the .config directory was modified. Issuing the command again in that directory reveals that a file called monitors.xml was recently modified. Here lies the problem.

The monitors.xml file contains the monitor settings for each user, including screen refresh rate. I simply deleted this file, and everything returned to normal. All this hassle could have easily been resolved if the monitor settings revert back to the previous settings if the user doesn't confirm the changes within a few seconds time. Despite all the trouble, Ubuntu is still my favorite operating system.