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Darkened screen after moments of non-use

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After several moments of non-use on a website...my screen on that website goes dark...not black...just goes darker. Like on youtube, pinterest, and any video-type website...The video/blogtalk continues with video and sound, but the screen is just darker and you cannot respond to any chat on that page. You have to refresh the page to get the fully bright colored page and chat. What is going on? This has just started in the last few days. Please HELP! Thanks... Carolyn

After several moments of non-use on a website...my screen on that website goes dark...not black...just goes darker. Like on youtube, pinterest, and any video-type website...The video/blogtalk continues with video and sound, but the screen is just darker and you cannot respond to any chat on that page. You have to refresh the page to get the fully bright colored page and chat. What is going on? This has just started in the last few days. Please HELP! Thanks... Carolyn

All Replies (3)

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Could you check to see whether you picked up an unwanted extension? You can disable ALL nonessential or unrecognized extensions on the Add-ons page. Either:

  • Ctrl+Shift+a
  • orange Firefox button (or Tools menu) > Add-ons

In the left column, click Extensions. Then, if in doubt, disable.

Usually a link will appear above at least one disabled extension to restart Firefox. You can complete your work on the tab and click one of the links as the last step.

Does that stop the "lights out" effects?

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See also:

If it works in Safe Mode and in normal mode with all extensions (Firefox/Tools > Add-ons > Extensions) disabled then try to find which extension is causing it by enabling one extension at a time until the problem reappears.

Close and restart Firefox after each change via "Firefox > Exit" (Windows: Firefox/File > Exit; Mac: Firefox > Quit Firefox; Linux: Firefox/File > Quit)

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Can you look for something called Tube Dimmer in the Windows Control Panel, Programs and Features. If it's like Windows 7, you can sort by install date to see what else was installed at the same time and possibly track down how it got onto your system.