I plugged my 1920x1080 HD monitor into the analog VGA output of my laptop. On my G3 ibook running 10.4.11 (with the screen spanning hack enabled many years ago), the old ibook detects and sets up the HD monitor as 1920x1080 60hz, millions of colors. Just like it should. Unfortunately, the new setup running 10.5.6 did not automatically show me a usable display on the same analog port on the monitor. It showed the monitor in the display settings and I could arrange it and all but the monitor just showed a bunch of lines. Stupidly, I clicked "mirror", assuming it would set both displays to the lower resolution of the laptop's monitor and I could get a display on the external just to verify that it was working. Nope. Now I get both monitors full of random lines when I plug in that particular external monitor. And, because OSX remembers the last settings used for each monitor, it automatically engages mirror mode every time I plug in that monitor. 
Other monitors work just fine. My 17" CRT is recognized perfectly and works in all resolutions up to 1280x1024 (highest the monitor supports). 17" LCD is recognized perfectly and even remembers that I drug the menu bar over there and slides it over whenever I plug that monitor in.
So how can I reset the configuration of the 1920x1080 HD monitor so the new laptop stops automatically going into mirror mode when it's connected. Heck, it'd be even nicer if I could turn off the mirroring and set the default resolution to 1920x1080 60hz.
Other monitors work just fine. My 17" CRT is recognized perfectly and works in all resolutions up to 1280x1024 (highest the monitor supports). 17" LCD is recognized perfectly and even remembers that I drug the menu bar over there and slides it over whenever I plug that monitor in.
So how can I reset the configuration of the 1920x1080 HD monitor so the new laptop stops automatically going into mirror mode when it's connected. Heck, it'd be even nicer if I could turn off the mirroring and set the default resolution to 1920x1080 60hz.