I have an issue with GameEngine (.blend attached)

Hello, the issue I have is this:

PROBLEM:

I have a game (very very simple) - a sphere that moves around when pressing the arrow keys (moves around a plane). When it goes over the edge, it falls off.

Well, this is what is SUPPOSED to happen. OK OK, the problem:
I move the sphere around the plane, and it sometimes moves randomly up in the ‘air’ (upwards) and sometimes falls through the ‘floor’ (plane) and sometimes both.

So… yeah… that’s basically it.
The .blend file is attached so you can see if you can tell the problem.
A video showing the problem can be found at:
http://uk.youtube.com/watch?v=GSrriwhozg8

Thank you for taking the time to read this, maybe watching the video and maybe getting the .blend file.

Attachments

game001.blend (194 KB)

See attachment

Attachments