I bought a new 3.2Ghz Quad-core Mac Pro a couple weeks ago with an Nvidia 8800GT video card. I received this Mac on Tuesday finally. I needed to upgrade from my Dual G5, and thought this would be the answer to all my prayers. Well, after a nightmare with Apple and FedEx with my box being shipped without an address, it finally came home. Sadly, I've run into one very annoying problem. When I switch resolutions, the system graphics get very choppy and ridiculously slow. Windows are hard to move, everything graphic-side is just a mess. Videos are slow to watch, it's all hell until I restart and it goes back to normal. So what steps have I taken? I called Apple upon noticing this odd problem. They had me reset the PRAM, repair a non-broken Hard Disk, restart multiple times, and a couple other things that simply didn't solve the issue. The tech-support person put me on hold for 15-20 minutes just to tell me that he doesn't have a solution. He thinks it's a hardware issue, I think it's a Mac OS X Leopard issue. Why? Because I have Windows Vista installed on a separate Hard Drive, and I switch resolutions like I do on OS X, and it doesn't replicate the problem. Now, that's odd. So, I have another OS X Leopard install, I switch to that, same issue. I tell the tech support guy all of this, and he doesn't know what to do with me. At this point he's just trying to get rid of me. So, I tell him that maybe I discovered a new issue with the new Mac Pros 8800GTs and OS X Leopard. I ask him if it would just be easier for me to take it to an Apple Store and get it checked out, and he says that I should. Tonight, I have an appointment to take my Mac Pro, and see what the verdict is. Hopefully it's not a hardware issue, and I can get my Mac back as soon as possible, and Apple can release a patch for this as soon as possible too. I head over to the Apple Store with a scheduled appointment. I give the Mac Genius a full run-down on what the issue is. I can replicate the problem with one of their 20-inch screens, but it returns to normal a few seconds later. He is able to see the lag with the graphics, and believes me. I tell him to test it on a 30-inch Cinema (which is what I have), and he says they can't. I wanted to simply show him the problem, so he can fully understand what was going on. He tells me all he can do is keep it for a day or two, and run diagnostics on it. Technically that should give them all the answers if anything is wrong with the computer itself. I tell him if the problem doesn't happen in Vista, but it happens in OS X, then it shouldn't be a hardware issue, right? He agrees with me. Finally, I guess our "15 minutes were up," and he asks me what I want to do. I tell him that I need my machine, and I am going to take it back home, reinstall Mac OS X Leopard 10.5.1 thinking the Leopard Graphics update was the culprit or 10.5.2. I erase my Hard Drive and do a fresh install, and it fixes nothing. At this point I have three options: 1. Get a video camera and record the issue, and show it to someone who can help me. 2. Find someone that bought a new Mac Pro with a 30-inch Cinema and a 8800GT. 3. He suggested I get a new one, but I told him I don't want it to be broken, and that getting another one would mean to wait another two weeks, and I need it for my work. What if it's Leopard causing the problems? I would have returned it for no reason. I will do step one and two first, hopefully this will reiterate to me that it's not a hardware issue, and simply an OS X Leopard issue, which I'm 95% sure it is. We will see. Otherwise, if I have a effective Mac Pro, I will have no choice but to return it for another one.