When I connect my laptop to an external display at home, it doesn't automatically extend the display, nor will it allow me to extend it. The Windows screen resolution dialog displays the error "Unable to save display settings" and the Intel driver dialog silently fails.
The laptop is a Dell XPS M1210 with an Intel GMA 950 adapter.
The same laptop works fine with my multi-monitor setup at work – 1 external display and 1 USB (DisplayLink) display. It also works fine when connected to my TV with the S-video output. It also used to work with my home display but has just stopped. I can't see anything that has changed on the laptop. The screen I can't connect to works just fine when plugged into a desktop.
This is the error:
I tried editing the registry as suggested here. I didn't have a key at HKEY_CURRENT_USER\Software\Microsoft\MobilePC\TMM. I tried removing the whole MobilePC section and rebooting, which didn't make any difference.
EDIT: This is what it looks like at work:
Screen 1 is the laptop, Screen 2 is connected to the VGA-out and Screen 3 is on the DisplayLink USB connection. This setup works nicely.
Best Answer
Have you tried changing the settings in the Intel GMA settings from control panel?
Update:
The display you have selected in the drop down(1. Mobile PC Display) appears to be the DisplayLink display that you use at work. Its odd that it shows up as active after it was unplugged. Have you tried the "Detect" and "Identify" buttons to see if it can figure out that the USB display is not hooked up anymore?
Per the DisplayLink user manual (pg 12 & 13), there is a off button to disable the DisplayLink monitor. This might free up the windows display settings. Try the Detect button again after having disabled the DisplayLink monitor.
As a last resort, you could try re-installing the DisplayLink drivers and the Graphics drivers.