Wowzers....

....
Your system, like mine, should run FSX as sweet as a nut!
So, as Garry suggested, you may have a problem with your original installation!
...or...
Like me...after clicking on the FSX Icon, you have to wait a while for everything to sort itself out, and load everything up, before the Sim actually starts to run, and things start to happen!
Paul....

....!
Win 8.1 64-bit. DX11. Advent Tower. Intel i7-3770 3.9 GHz 8-core. 8 GB System RAM. AMD Radeon HD 7700 1GB RAM. DVD ROM. 2 Terra Byte SATA Hard Drive. Philips 17" LCD Monitor. Saitek Cyborg X Fly-5 Joystick. ...and a Briggs and Stratton Petrol Lawn Mower.