Photoshop :: Appears To Save - But Hasn't?

We hit save and everything appears as though it is saving, only to find out after we've closed out the file that it hasn't been saved. Or portions of the work we did were saved but not the entirety, and out of chronological order. Though we are connected to a series of networked servers, we do all of our work locally and save locally before copying the files back to the server. This has affected 5 people so far and started occurring within the last two weeks. We've been doing this sort of work for over 4 years here and never encountered this problem.
 
We're pretty desperate to see if there's some sort of answer. So far our only solution is to keep saving the file in different locations on our system with different names, just in case.
 
We are all running on Mac OSX Lion 10.7.3 and Photoshop CS5 12.0.4.