My runways disappear..

[Michael Ellen 1095800]

Sometimes when I'm just about to touch down, the runway starts to disappear in certain points.. I had a suspicion it was to do with some freeware orbx scenery that I installed so I uninstalled it and it's still happening. Take a look -

 

http://s732.photobucket.com/albums/ww325/ellzeez/?action=view&current=norunway.jpg