I would be very grateful if anyone could offer advice or insight into a problem which seems to have manifested itself over the last couple of weeks for which, I am unable to find either a cause or solution.
I run Windows 8.1 using a screen resolution of 1920x1080x32 (with which I have never had a problem), which means that FS9 opens in a minimised window. As usual I make my selection of aircraft, scenery etc, and then hit the “Fly Now” button. Once the sim has started I then hit Alt+Enter to go to full screen. Roughly 6 or 7 times out of 10 the screen will go to “full” and the sim performs as it should.
However, on the other occasions hitting Alt+Enter causes the screen to blank and after a few seconds a small window appears telling me that,
“Microsoft Flight Simulator has encountered a problem and needs to close. Microsoft is gathering information etc, etc,.....”. (I think we all know how much weight that statement carries!!)
My keyboard is a Logitech wireless, and thinking that perhaps that may be the cause of the problem, I tried a spare Logitech wireless and then a wired keyboard with the same result. Selecting “Full Screen” from the View menu did not work every time either.
I have now reached the (narrow) limits of my expertise and hope that someone can at least throw a little light on what has now become a frustrating annoyance.
My thanks in advance for any guidance anyone is able to offer.

David