Well I am having the same problem now  it was working fine till I reinstalled all my software in my computer after a crash  I had this trouble before and solved it but I cannot remember what I did now .If
I am fast I can click on File and options and connections and set it to FSUIPC  and I did manage to build a data base for FSX but then it will not work  still crashes  and if I just run it as admin it only stays up for 20 or 30 seconds  very frustrating  .. put the file in and have checked all the sim connects  but nothing is working