Scene editor loses camera control using terrains

I’ve just started using Unity and while using the terrain tools the Scene view within the editor will no longer respond to camera controls – middle click to pan, right click to mouse look.

I can still interact with the scene, select objects, use F to focus, use the Perspective/Ortho gizmo, etc. I am also able to right click/middle click things in project view and elsewhere in Unity. There are no error messages in the console, the only other object besides the terrain is a Directional Light set to sun.

Points when it has happened: raise/lowering terrain, paint texture terrain, and just now with smooth terrain.

If I save my scene and relaunch Unity everything goes back to working.

#Terrain info:##

2000x2000x300, detail 1024/8pp

##Version info:##
Win7 x64, Unity 3.5.2 Basic/Indie

Is there key I’m pressing by accident that “locks” the view, or is my terrain outside of what is expected?

Since it’s been a month and no answers, here’s what I did to get through:

  1. Try not to zoom in too much, this seemed to make the problem happen sooner.
  2. Use small strokes - meaning don’t hold down the button too long, repeated shorter clicks seemed to help.
  3. Once camera control is gone, do whatever is left at that position, save and reload. Good to save anyways.
  4. Mixed results with varying scene preview size (2x3, 4 split etc), I couldn’t find anything conclusive as to which lasts longer.

Since it’s been a month and no answers, here’s what I did to get through:

  1. Try not to zoom in too much, this seemed to make the problem happen sooner.
  2. Use small strokes - meaning don’t hold down the button too long, repeated shorter clicks seemed to help.
  3. Once camera control is gone, do whatever is left at that position, save and reload. Good to save anyways.
  4. Mixed results with varying scene preview size (2x3, 4 split etc), I couldn’t find anything conclusive as to which lasts longer.

So I just found this error as well and I just found a quick fix I think. Not much of a fix, but if you move the camera how you would normally, but behind you it seems to work. So if that seems confusing just hold shift + right click and then A or D but in the backwards direction. I seem to be able to move normally (obviously except for the fact that I have to do it backwards =/).