This repository contains an example of limation of the physics engine of gazebo.
If you clone it and create a catkin_ws try:
$ roslaunch simple_robot_description rviz_simple.launch
$ roslaunch simple_robot_gazebo simple_robot_gazebo.launch
In this case, if you play the simulation or the joint_link appears in the origin, or after some seconds the simulation colapse and then goes to origin.
Some one you know what is wrong?