I don't think there is a problem here that needs resolving by either Jim or MA3....
I'm running 2560x1024 across two 5x4 monitors, (@1280x1024 each). - The largest window that does not pan is approx 2560x800.
I think the solution, (if there is one), is either with your video card settings, or with Windows 7.
Why would you want to "stretch" MA2.6 across three monitors? - MA2.6 is designed to show the same image on all screens, its image is not intended to cover more than one monitor, in the way that MA3 can.
Well, 3.0 doesn't work right on my system, I don't think microsoft is going to look into serene screen not working on win7 so that means Jim will have to find out what is wrong. It's not just my computer as the thread linked above shows several other people having very similar issues. My video card settings are stock, I haven't changed anything from what they were when I installed the latest version from nvidia.
As far as why would I want to span 2.6 across my whole desktop, why wouldn't I want to do that? If it can't then that is what I was asking, is it possible?.....so I take from your statement that it's not possible in 2.6?