[ros-users] Gazebo and Laser simulation

Hi!!
I am simulating a robot with a laser in Gazebo and it works quite well, but there are times when there is a desalinate between the orientation of the robot and the map, I mean the border of the map doesn't match with the laser points. As actually I dont know to much of gazebo and I didnt find anywhere this error, now I am asking to the list. It must be a problem with the tf, but the weird thing is that I do not have always this problems, just some times, but when it appears it continue like this until I finish the program.
I would like to add an image for u to see, but each time I try to add image my msg is rejected.

Thanks in advanced

Nicolas