I have a customer who has bought a second monitor for his laptop. The problem is that he can't change the setting to have his desktop extended across both monitors. The same desktop is displayed on both monitors.
When he goes into display properties, the second monitor is there but greyed out. I got him select it and check the box which extends the desktop onto that monitor. When he applies the changes and clicks ok, nothing has changed. When he goes back into display properties, the box is unchecked again.
I thought perhaps this was happening because he doesn't have administrative priviliges. I got him to look at his user account. He is an adminstrator.
So why isn't the setting being saved when he changes it?