Strange Terrain Problem

My terrain changes from looking like this:

alt text

to this when I begin editing the terrain:alt text

I’ve tried everything in the settings tab of terrain but can’t fix it.

Any ideas?

Use “Paint Height Tools” and set Height to your normal terrain height.

The second tool from the left is the Paint Height tool .

This tool allows you to specify a target height, and move any part of the terrain toward that height. Once the terrain reaches the target height, it will stop moving and rest at that height.

To specify the target height, hold Shift and click on the terrain at the height you desire. You can also manually adjust the Height slider in the Inspector.

Now you’ve specified the target height, and any clicks you make on the terrain will move the terrain up or down to reach that height.

http://unity3d.com/support/documentation/Components/terrain-Height.html