Crash when trying to Save As

Deleting Saved did not solve this for us. Any understanding as to what else causes this? It was only encountered a couple of days ago, but is happening on two projects regardless of machine. On is a clone of the other. The original one had not been updated or touched at all for several days prior to the problem, and the clone had been worked on just fine for a couple of days prior to the problem of crashing when trying to Save.