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I have Ubuntu 12.04 (Precise) OS and I actually can't tell what has caused this weird thing to occur.

Sometimes, the screen just turns off. Then it immediately turns on thinking it's in digital mode (DVI) even though it should be analog mode. And then it goes to analog mode and then it might even have a progress bar showing that it's initializing itself (says "auto adjusting").

This has started occurring only today. I think the only thing I’ve done is to do a small update for the OS. Sometimes it occurs only after a long time since boot, but when it occurs, there is a high chance that it will occur soon again.

The screen is Samsung syncMaster T220p.

Is there maybe a way to go back to previous state of the OS, like on Windows? Maybe something went wrong in the settings of GNOME?

I've connected the problematic monitor to another computer (Windows 7) and it worked fine, while connecting a different monitor to Ubuntu OS (which also worked fine).

Today, I've connected the problematic monitor back to Ubuntu OS computer and it has worked fine for several hours and then the problem has occurred again.

I think it's best to replace the monitor, but it would be nice to know if someone can tell me if it's possible to fix it in another way.

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Do you have another monitor or display to test with? (swap display, see if the problem persist on the other computer -> HW problem in monitor, or with the other display onthe original desktop). Then add the results of these tests to the post. – Hennes Aug 15 '12 at 11:29
i've now replaced the monitor . i don't know what i hope to conclude from this . if it's a hardware problem , it's very odd since the monitor is just a one year old , and it's a really good one. – android developer Aug 15 '12 at 12:46
Well, it could be the monitor, a broken cable (bad contact?), the graphical card or the software. If the 'broken' monitor works fine on another PC then you can exclude one item as problem source. etc etc. The real problem is if it actually is a problem with the monitor and the software (wasd that small update an update to X?) – Hennes Aug 15 '12 at 13:13
ok , i've replaced the monitor with another one , and it works fine . the weird thing is that connecting the problematic monitor to another computer (which has windows 7 OS) didn't show those problems. it showed other problems: when connected/disconnected while the OS is running , the monitor and another one that is connected are both turned off (?!) , so only if you restart the computer they all work fine. – android developer Aug 15 '12 at 17:20

I also had problem, with Ubuntu x86_64 with CRT monitor. One suggestion I found, and worked for me was to unplug the monitor cable from back of PC (DVI cord) and keep monitor powered down.

Once you boot into Ubuntu ( do I know..well, just guestimate approx 5 min, say), attach the still powered down monitor cable (DVI cable) in the back of PC. Start the monitor power.

This could be due to nVidia driver update issue (in my case). By following the approach I mentioned, the Ubuntu 'thinks' it is a generic monitor and will not both shutting down on you. Although it will use 800x600 or 1080*768 resolution (because the graphic driver incompatibility).

Then there is another issue with x86_64 linux. Only 386 linux (SL6, Ubuntu 386) in 32-bit mode worked with 1440*1200 resolution. This makes me think that the nVidia driver for x86-64 is and has been alway an issue.

Hope this info may work for you.

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