Windows Updates are causing issues with the AutoCAD Architecture (and AutoCAD MEP) Project Browser. A recent Knowledgebase article points to Microsoft updates MS14-037 (KB2962872 – July 8, 2014) and MS14-051 (KB2976627 – August 12, 2014) as the culprits. I’ve had a couple of customers call with this issue and following the uninstall procedures in that article resolved the issue. (Remember to hide them to prevent re-installation at a later date).