Skybox(sphere) problem with cameracontrol <> mousemovement

Hello iam new here and also a noob with Blender, hope my english is good enough to understand my problem.

I would like to build a small game with 3D controls like in EVE-Online.

I made a Skybox wherin a spaceship is placed in the center with 2 scripts i got from the web it uses the mouse (with pressed LMB) to move and Rotate the Camera aroud the Center.

So far so good…

Now my Problem:
I whant the “Horizon” to NOT rotate so that when the camera is the same “hight” of the Spaceship the rotation-degree of this Horizon is 0° (if it would be a planeboth wings are same hight) but during the rotation by mousemovement this Horizon turns so that former or later the spaceship is Upsidedown.

May someone has some hints what may went wrong or how i can do this in Blender also any Tutorial about Moving Camera arround an Object in center with the behaviour i described would help me?

You will find a .blend file in the attachments (I use Blender 2.49b)

Greetz Sascha


space_sky10_flyship_2.blend (262 KB)