Has anyone ever seen this dialog box before? It seems to pop up on just one machine here, intermittently, in Revit Structure 2013. It's been doing it for a couple weeks, with lots of reboots along the way. It does it sometimes when Synching with Central, sometimes when an element is selected. It can't be stretched any larger, and all it has in it is a drop-down list of all the files linked into the project. I wonder if it's some perverse mutant form of the Properties window. Oddly enough, it seems to be largely benign, unless you try to close it while the Synching with Central is actively going on. I suppose it means that I really should re-install Revit on the machine where this occurs, but if anyone knows of some setting or software conflict or something that affects this, I'd love to hear. Especially if it gets me out of having to reinstall the software.