Cannot change dekstop background

[riaaz66]

Hey,

I've a mac mini, with two 24" Cinema Led displays. One display is connected directly to the mac mini (main screen) and one display is connected through a DVI-to-Mini-DisplayPort Converter from Athlona (secondary screen).

Yesterday I rebooted the machine and since the reboot I cannot change my main screens desktop background. I tried every solution from several fora on the net, but did not succeed to change it. I only have a solid gray colored background. Normally, when you select a wallpaper, it instantly changes the background. Now it doesn't. You can see it change in the "Desktop & Screensaver" menu, but nothing happens in real. Changing the background of the secondary screen is no problem.
When I restart the machine, you can see that the solid gray colored background goes away and the original chosen wallpaper appears, but then closes because I restarted the system. On start-up of the system, you can see the original chosen wallpaper again for a few seconds, while the machine starts applications to open at login, and then suddenly changes again into the solid gray colored background.

Can somebody please help me with this issue???

 

[DewGuy1999]

You could try this:

Resetting your Mac's PRAM and NVRAM

 

[riaaz66]

You could try this:

Resetting your Mac's PRAM and NVRAM

Hmmm..thanks....but it didn't work.
Any other suggestion. It looks like that the solid gray background on screen 1 is a layer above the originally selected wallpaper. Because when I restart the computer, the originally selected wallpaper appears when closing the machine and when starting up the machine.
Any other suggestion.

 

[DewGuy1999]

I was hoping the PRAM/NVRAM reset would work. Have you tried a different wallpaper? You mentioned doing a restart, have you tried a shutdown followed by a cold boot? Also, any luck changing the background on your main display if you disconnect the secondary?

 

[BigDukeSix]

I suggest just trying one monitor at a time, connect first through the primary monitor connection and then again through the DVI connection to see what happens under those circumstances. Let us know the results of your test.