Got a ton of errors and warnings about not finding objects and thus not being able to set attributes and not being able to perform merge vert operations. I was on the master render layer, all display layers were visible and the panel was set to show all but the only things visible were the desk and some area and point lights even though the outliner had many more surfaces listed. I don't know if this is what you're getting or maybe something was lost in translation but those phantom surfaces had MR coughing up blood, it was crawling and throwing errors about ignoring unnamed objects and empty surfaces. I deleted them and the scene rendered in seconds.