Height map problems NOT SOLVED IN THE MAP ISSUES THREAD

[Rasiel]

It all started after I downloaded a few meshes and created some new Terrain textures. The meshes are working fine as far as I know, although I made a new terrain and mask and the mask worked fine but it's the height map that is messing up. Whenever I try to put the height map in it immediatly crashes or it works but when I test it, it crashes. OR I test it and I end up falling through the map or this happens.




See the mesh just extends endlessly in the sky! Sometimes it's a whole wall that does that!

Now the strange thing is that any other terrain I have previously made before works fine. In addition to me crashing in the map maker, sometimes I even crash when I press quiet! this isn't a problem in game, but it is when I'm testing a map!
 
Please help! Thank you (: