Greetings from a noobie to FlightSim.com. I've been a MS FlightSim enthusiast going back to the first edition when 3D scenery was "stick outlines".
I have been successfully running FSX Acceleration with 3 displays, using 2 ATI Radeon HD4850s for 4 years. I started with three 20" monitors (1440x900x32) with no resolution recognition problems. I then upgraded the center monitor to a 23" monitor (1920x1080x32), and FSX was able to keep track of the two different screen resolutions. Most recently, I replaced the two 20" (outboard) monitors with two 23" monitor (1920x1080x32), matching the center monitor. I also upgraded my GPU with a Radeon 6950 2GB and successfully operated FSX in eyefinity (5760x1080x32), although with very poor frame rates.
I decided to test things out and went back to the two Radeon 4850s, using the three 23" monitors. To my amazement, FSX held onto the center 23" monitor resolution, but downsized the resolution of my outboard 23" monitors to 1440x900x32, the 20" display state prior to the monitor/GPU upgrade.
I uninstalled/reinstalled FSX Acceleration, keeping only my flight records thinking that would solve the problem. Sadly, I'm still experiencing the same issues. My guess is that FSX held on to the "old" resolution setup through the uninstall/reinstall process.
Any help would be appreciated.