Re-install 10.2.1
this stopped the problem that I was having.. (same thing.. cant save file, busy, blah, blah, blah)
Seems that minor BUG fixes.... managed to DISABLE..... ADOBE's functionality...
GO FIGURE???
when i called Apple on this one... They started pointing fingers @ ADOBE...
I used to get that message. I don't anymore and don't know what caused it, but the way I got around it was to save a copy of the file. Go to File>Save a copy. For some reason this worked. It's annoying to have to do this every time, but it's even more annoying not being able to save all that hard work.