I have noticed a problem since I have done a clean install of 10.6. I have a Unibody Macbook hooked up to a Dell 2409 monitor. In 10.5 I was able to use my macbook as an extension my desktop. Now all it shows it just the regular snow leopard background on the macbook and my regular desktop on the dell. I am in display setting and under arrangement, it show no windows inside. When I click on mirror desktop, the display windows come back in the "arrangement" tab. If I click on "Mirror Displays," it works ok doing mirroring the image of the macbook. I want to use the Dell as the primary display and use the macbook display for things like Itunes and IM. Right now I cannot drag anything from one display to the other. This is becoming a problem because I cannot use my macbook screen at all to drag any apps to that screen. The weird thing is that when I open some applications, they open on the macbook screen. I am able to moved the mouse around on the screen in sync with the Dell, but I am not able to click on anything in the macbook. I bought SwitchResX and so far, that has not been able to help me. Thanks for your help, I need any I can get. This is getting very frustrating. I really don't want to have to do a full format and reinstall everything just because of this one issue. Thanks guys.