I am using 2014 Plant 3D. My 3D drawing are losing all intelligence. E.G. i can not modify pipe runs or components, selecting a pipe and referencing the properties box give no information on the part selected. Sometimes when this happens i will see an information cloud pop up in the lower right hand corner saying "oprhaned fasteners are detected. This drawing contains orphaned fasteners, due to changes in an xref." I am the only person working in plant and nothing has changed that i know of.
It sounds like your project is out-of-sync with the database. A couple commands to help get it back in-sync are PLANTAUDIT and AUDITPROJECT. Basically PLANTAUDIT deletes entities from drawings that are no longer in the project database and AUDITPROJECT deletes entities from the database that do not exist in the drawings.
http://docs.autodesk.com/PLNT3D/2014/ENU/filesPLNT3D/GUID-609AA28E-55D5-4945-9D17-F15B72BB1190.htm
http://docs.autodesk.com/PLNT3D/2014/ENU/filesPLNT3D/GUID-E3D4D4AA-972A-400D-8BE8-2EA3B5FC9401.htm
If you are recovering from a crash, you may need to retrieve a recent back-up for some of the drawings and go from there. Some of the P3D piping and entities may need to be redone in order to get the Plant intelligence back for some of those items. And be sure to do frequent, if not daily back-ups.
Worst comes to worst, remove the drawing from the project and add it back in. There is a backup copy of the data embedded in the drawing file. It will repopulate the database if you add it back to the project.