I also have the same problem.1. I installed in <C:Program Files(x86) Microsoft GamesMicrosoft Flight Simulator X> once.2. Activation was performed and it was used satisfactorily.3. FSX of C drive was uninstalled, and it installed in other drives.4. The present composition is only FSX with Acceleration, PMDG747-400x, and PMDG737NGX-800/900 sp1b.5. PMDG747-400x can be selected satisfactorily. If PMDG737ngx selects, FSX will crash.CPU:Intel Core i7-2700kM/B:ASRock Extreme7 Gen3VGA:MSI GTX580 LightningMem:DDR3 PC3-12800 4GBx4SSD:Intel 510 SSDSC2MH120A2K5HDD:SEAGATE ST1000DM003OS:Windows 7 Ultimate 64bit