I had the FSX demo installed on my WINXP system along with my FS9 a while back. I have since uninstalled the FSX demo because of an issue I had with loading saved flights in FS9.
Instead of loading the saved custom flight, I would get the default FS9 flight. You know, Cessna at Seattle. After uninstalling FSX, my saved flights worked once again. A definite clue to the problem was that all the icons for saved flights displayed an FSX image.
This sounds to me like a registry problem. FS9 saved flights are saved in "C:\Documents and Settings\...\My Documents\Flight Simulator Files" and I am wondering what directory the FSX saved flight are stored in.
Bottom line: has anyone else experienced this with the demo or full install of FSX?