May I ask why you've activated the Windows 7 compatibility in the first place? When you enable OS compatibility, Windows will place an sort of 'emulator' between the running program (and all libraries that are referenced by it) and all instructions are 'filtered' and altered when needed. Microsoft self only advises to use the compatibility feature when you to running a program that's using a specific Windows version component. Most problems with software initially designed for Windows XP, is to let the program run under administrative privileges. Settings it to Windows 7 compatibility mode also means that if a library (dll) running under FSX call an obsolete instruction it will crash (windows will simply block the instruction).
