After upgrading from Gazebo 2 to Gazebo 7, shadows stopped displaying properly in my Gazebo worlds. At first it appeared that the shadows were not showing all-together, but then I noticed that they appear in the background at seemingly random locations as I zoom in and out. A screen shot of the standard Empty World with these random shadows is shown below. I am curious if anyone has had a similar experience and/or has any ideas what could be happening.