Object disappearing in GE

I have a problem durong a kind of travelling on blender. The character is moving from left to right in the scene. The center of armature of character (object) is staying at the same place during all the travelling. The camera is following it controlled by python (and the localPosition variable). At one time, the character just disapper. If I unzoom and run the same action, I can see the character during all travelling. More weird, if I move the camera at this moment, the character is still visible except when the camera is looking at him. Any idea?
Here is a blend file : http://box.creapach.fr/MABEL/MPM/. Quite complicate to export my control interface for the moment, I’ll try to make a small one on wednesday (didn’t have much time up to there).

well, I would like to help, or at least, try, but your “setup” is “uncheckable”…animations seems not working…and the camera view is quite weird?!