A trick I use when setting up a TH2G is to set up in singlescreen 1680x1050x60 first, then go to a 5040x1050 desktop after a reboot. Example:
1. Update the firmware on the TH2G to the latest if you haven't already.
2. Install the latest Matrox PowerDesk (2.06 I use).
3. Run the Matrox Setup Wizard, choosing Singlescreen (not TripleScreen), then select Widescreen (not Standard aspect ratio, as 3 x 1680 x 1050 will not appear for me if you don't change this setting), manually select 1 x 1680 x 1050, then save and apply. Run through the setup until the system asks you to reboot, then reboot the PC. When it restarts, the setup completes.
4. Go into the PowerDesk and save the single screen setup as a favourite (use swap display first if the wrong screen is being used in single screen mode).
5. Quit out of PowerDesk, right click on the Desktop, go to Personalise or whatever menu option takes you to your screen resolution (depending on which version of Windows you're on), then move the slider out to 5040x1050.
6. Open PowerDesk again and save the triplescreen setup as a second favourite.
7. Setup hotkeys.
I have never had a machine that couldn't do it this way, but in saying that, I have always used Nvidia cards. Has worked for me on Windows XP, Vista, and 7.
I also have an ATI 5850 in another machine, so I am familiar with the ATI CCC interface, but I use the in-built Eyefinity to get a triple display setup with a DP-DVI adapter. I assume the single monitor is not set up as part of a group or anything?
