Error using DRCSim (Gazebo) on hydro - Unable to read file[.../atlas.urdf]

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Hi, I'm using DRCSim 2.6.6 and gazebo 1.8 on ROS Hydro. When I roslaunch atlas.launch this error appears:

failed to start local process: /opt/ros/hydro/lib/stereo_image_proc/stereo_image_proc __name:=stereo_proc __log:=/home/gustavo/.ros/log/eca8b864-fb95-11e2-b1fd-001e65d8adfa/multisense_sl-camera-stereo_proc-6.log
local launch of stereo_image_proc/stereo_image_proc failed
[multisense_sl/camera/stereo_proc-6] process has died [pid -1, exit code 127, cmd /opt/ros/hydro/lib/stereo_image_proc/stereo_image_proc __name:=stereo_proc __log:=/home/gustavo/.ros/log/eca8b864-fb95-11e2-b1fd-001e65d8adfa/multisense_sl-camera-stereo_proc-6.log].
log file: /home/gustavo/.ros/log/eca8b864-fb95-11e2-b1fd-001e65d8adfa/multisense_sl-camera-stereo_proc-6*.log


Error [parser.cc:636] Unable to read file[/usr/local/share/drcsim-2.6/gazebo_models/atlas_description/atlas/atlas.urdf]
Error [parser.cc:710] Error reading element <world>
Error [parser.cc:369] Unable to read element <sdf>
Error [Server.cc:284] Unable to read sdf file[atlas.world]
Error [ConnectionManager.cc:123] Connection Manager is not running
[gazebo-2] process has finished cleanly

This appears after a stereoimageproc error. so, Is this only gazebo issue or is related with the previous error?