collision issues

Hi,
my name is mauro and I´m working with 2 friends on a 3D rpg as our graduation project. We were using the Panda3D engine so far.
Our game is actually in a 3rd person view, so you control the main character through the stage.
We´re having serious problems in making the character collide with the enviroment. We tried to make a Collision sphere around him, and we activated the collision with the geometry. Unfortunatedly the character himself is a geometry, so, since the sphere and the character are atached to the same node, they keep colliding and making chaotic movements.
How can I make my character collide with the enviroment?

And by the way, how many polygons does the panda model has?

Thanks
Mauro