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Josh Kahane

macrumors 6502
Original poster
Aug 29, 2006
Suffolk, UK

So I have a rather frustrating issue. After installing SwitchResX and now uninstalling it reseting to factory settings I have been left with a pain in the backside.

I have a 20" iMac (1680x1050) and a secondary monitor (1280x1024) and now I and firstly, stuck In some kind of mirror displays mode, even though it is not enabled in system preferences. The wallpapers, resolutions and general screen contents is different except it keep mirroring the mouse movement from my iMac screen.

Secondly, in system preferences, under the Arrange tab, there are now displays in the box, I have an empty box meaning I cannot arrange my displays.

This is a right royal pain, hope you can help, thanks.


macrumors 65816
Jan 9, 2007
The two things I can suggest are to check the 'Mirror displays' checkbox, close system prefs, then reopen it and uncheck it to see if it will go back to dual displays.

The only other thing I can think of is to click the 'Detect Displays' button to see if that resets things so you can work with both normally.

Oh, you could try starting up without the external monitor. That might make it forget about the external monitor. Shutdown and plug the monitor in again.

I guess that was three things. :)


macrumors newbie
Jun 12, 2011
This post is a bit past its prime, but if someone who is having this issue happens upon this post, here's my thoughts. Try deleting the file in [root]/library/preferences/ and[bighexnumber].plist in [root]/users/[username]/library/preferences/byhost/.

Then reboot and reset the PRAM (holding cmd+opt+P+R before the chime until the computer restarts and chimes again)

good luck.


macrumors newbie
Apr 16, 2021
EMonkey: Thank you very much for the post. Perfect solution for my late 2008 MacPro, 30 & 20 inch Cinema Display. Blessings.
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