OK, I have a couple of users with a bizarre problem. We're using AutoCAD 2011 with a custom add-on package, Shipworks. Lets us put in shipbuilding specific geometry, and the like. The problem we're having is that some blocks on drawings are now showing up empty. The block is still there, it's not in the purge list, the drawing thinks it's being used. When you use block editor, there is no longer any geometry in the block. The drawings MAY have been opened in AutoCAD Mechanical at some point (sorry, can't convince them that if they don't need MEchanical, don't open it!). Has anyone ever seen anything like this going on?