For VFR Airfields for FSX to run smoothly and without any problems at least Service Pack 1 is required.
This is due to the fact that the FSX that you buy off the shelves has a bug in it which means that the base images (the images that are like the carpet of the airports and then the runways, taxiways etc sit on top of this base image) don't display propperly some of the times you load it up.
So you can see the base images correctly every time then you will need to download the SP1 update available from here:
http://www.fsinsider.com/downloads/Pages/FlightSimulatorXServicePack1.aspxThis will fix the above problems and you won't see any undesired results
Regards
UK2000 Team