I am running OS X 10.5.7 on a Dell Inspiron 1525, using the guide at the Mac Your PC website.

My problem is that when using an external display, Extended view works fine but Mirror mode causes display issues common with the x3100. I turned on Mirror mode before I knew this and now I have no way to use an external monitor at all because I can't "roll back" the preference to Extended view. I can't interface with System Preferences because the machine is unusable with a secondary display plugged in.

I want to know if there is any way to "reset" the Display preferences without re-installing OS X. I have already tried a new user account and reinstalling the kexts.

1. Boot without the external monitor connected.

2. Terminal:


rm -f /Library/Preferences/com.apple.window*
rm -f /Users/"USERNAME"/Library/Preferences/ByHost/com.apple.window*
rm -f /Users/"USERNAME"/Library/Preferences/ByHost/com.apple.pref*

3. Done 

Is there a way to reset the resolution selected also?
Well, me idiot, i tried to switch to 800*600 on my q1 ultra using the built-in control - oops it thinks it's out of range and, bummer, shows nothing on the screen. Vga out never worked, so now i have a runnin os without the screen. Any ideas on how can i reset the resolution? Reinstalling just the drivers with flushing cache didn't help. I now I can redo it from scratch but it ain't something I really want.

Any suggestons here?

Yep same problem here,
I'm using an Intel GMA X4500 (same driver, same problem)

The only resolution I get on a external display is 800x600, and, when I change it, it says: Out of range

Any suggestions, help ?

same problem here