Hi, I run dual monitors with my Mac Pro (first intel version) I have a samsung and an old apple monitor. It worked fine until I disconnected everything to fix the tangled cord issue. I put it back together and the apple monitor is recognized but the screen is black. (yes, I double-checked to make sure it's on.) I know the mouse travels to the black screen because I opened a finder window which did not show up on the samsung screen and after some 'fishing' I was able to drag it from the black screen to the samsung screen. The old apple monitor uses the VGA port. Any help is appreciated.