I got the UIAutomationCore.dll in my FSX main folder now and tuned the bufferpool up to a point where the screenflashes are minimal, when returning from map or flightplan page back to my aircraft. I still have some fast flashes and I can see a strange texture in the window, but that for a fraction of a second and even after 3 hours flight, I cant seem to trigger the black areas and missing parts of the picture anymore.

I'm still looking for newer UIAutomationCore.dll, the one I've got now is from 2008, but so far things are going very well, better then ever before.

Hope I can keep this up and maybe even tune it a little further, but for now I'm glad I got things working in a way that I can make a decent flight and dont have to worry about things getting messed up.
Thanks a whole lot guys!!!

I would try to remove that ac (save it in another place), and try again.

If i understand you right!??
This is the first time i ever heard of a flightstick, telling how to start up a sim/game 

Starting FSX and maintain these two keys.... that reminds me something... perhaps this forces FSX to generate a totally new FSX.cfg... that would explain why all your tweaks were gone...

I'm completely baffled now...

I reinstaled the whole machine again, after trying so many different things and instaling and deinstaling programs and addons and I had everything running perfectly again, everything seemed to work propperly and the movements and picture were so smooth, but now all for sudden I'm getting loads of problems again. Only thing I did was instal a couple of side programs like vroute, ultimate checklist, a demo of SimplatesX and a couple of aircraft addons.

-The settings of my controls within FSX are gone every time I start up FSX. Sensitivity and nulzone, as well as the control axes I programmed for mixture and prop.
-When I ask for pushoff, with a simple shift-P, so I dont ask to turn, the push does turn somehow and when I ask to turn in the push, it keeps going staight out.
-I always had the aircrafts drift off to the left on the taxiway and when taking off, so I made it easy for myself and activated autorudder and the aircrafts went perfectly straight out, but now from one moment to the next, they start drifting off to the right. When I try to steer, the slightest movement of the rudder already makes them turn enough to not be able to keep the aircraft driving straight out, I have to steer left-right-left-right and the aircraft keeps moving from side to side on the taxiway. The movement of the rudder is minimal, one tick less and it doesnt turn at all.
-I entered my heading at 035, the coarse of the runway straight out, but when I took off after taxiing and activated the AP, my aircraft turned a hard right and checking the heading indicator, it was set to 172 all for sudden.
-Every time I change frequencies on the radio, my ATC window disappears.
-Every time I change camera view, all my instruments on my right monitor (GPS, engine panel, electrical panel) disappear.
-When changing altitude the aicraft wil not automaticly set the VS and I have to do it by hand.
-When I'm already descending, ATC keep telling me to please expedite my descent
-The beacons next to the runway wont show up untill I'm just several yard from the runway, I cant see them when flying up to it.
-Once landed ATC tells me no less then 8 times to exit next taxiway, even before I had a chance to reach the first upcomming taxiway and it keeps telling me to exit next taxiway, even after entering the taxiway.

Those are all things I've never seen before, except for the instruments disappearing after changing camera view, not even with all the issues I've had before with FSX.
Does anyone have any idea what is happening here?