are you just trying to save an AE project normally? (ctrl + s)
or are you trying to export the project using some plug-in?
i need to know more about the situation at hand to be able to help.
Hi there: I have been getting this error too when I try to save an AE project (normal save: control+S); so there's no way to save the project and quit, you can only force quit out of AE. Any suggestions what to do? (AE CS5.5 on Mac 10.7.4 if that helps)