Sometimes when I start editing vertices on brushes, weird things start happening. They aren't invalid solids. And somethings one face on the brush disappears (giving complie errors)
Heres an example http://i28.tinypic.com/2elyyw4.jpg
As you can see, the solid has a 'dent' (made by me) on the right side, yet the camera shows it being full.
Whats happening?