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I have the ATI graphics manager (Catalyst Control Center) configured for my external monitor, attached to my Toshiba laptop, and the external monitor is recognized by this utility. However, the monitor shows up as "unknown" in the Ubuntu> monitor> preferences, and the monitor itself shows the message "No Signal". The laptop is dual boot, with Windows Vista, and I have the same problem with the monitor signal if I try it in Vista. However it was all working fine only days ago in Vista.

The same external monitor works fine on an ancient Dell, and is recognized in monitor> preferences, so I know it is not a problem with the monitor or the cables.

I see that there is a file xorg.conf (/etc/x11/) that seems to hold all the right info regarding the ATI graphics card, and another xorg.conf (in /usr/share/doc/xserver-xorg-video-nouveau/examples), which has minimal info. Do I need to be editing these?

Any ideas?

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I am having the same problem, too. The monitor does no recognize output from the laptop, and the laptop does not recognize a monitor being there (connected by VGA). Unfortunately, the automatic detection does nothing, because neither seem to realize that they are supposed to detect something... – annac Jul 29 '11 at 17:09

I have experienced the same trouble with my notebook and its ATi CCC. With a tool found on this site my external monitor is recognized immediately after plugging in. You will find a PPA to add so you can install it easily without fuzzing around in the Xorg.conf.

`sudo add-apt-repository ppa:hughescih/ppa && sudo apt-get update && sudo apt-get install autoswitcher

` Keep in mind that adding PPA's might be causing trouble to your system.

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