I am currently working with env_projectedtexture and a prop_dynamic. The prop_dynamic is a fan, which spins (parented to a func_rotating). My problem is, when the visgroup the prop_dynamic is in is not being rendered, neither is the prop_dynamic and the shadow of the fan (which is still visible) disappears. How can I keep the prop/shadow rendering?

Go to http://developer.valvesoftware.com/wiki/Func_viscluster, and just set it up so they can all see each other.