I was having the same problems as you described above. I finally solved the problem by doing the following:- Make sure you have the latest drivers for your video card, sound and most importantly your motherboard;- If you are over-clocking your processor return the clock settings to it's original settings, in other words do not over-clock your CPU;- Don't play too much with your fsx.cfg file, chances are you will make things worse by tweaking it too much.My FSX installation is running smooth after making the above adjustments. Hopefully it will work for you as well.Jorge