I have exactly the same problem but not only when saving. In my case it is enough to open the project. In english this error message should be something like "Refreshing of Display are putting into queue". In my projects the code completion is broken after this message.
This happens with projects created with flexmojos. If I create a new project in FB4 there seems to be no error.
Has anybody a solution?
Can you file a bug and attach your workspace log the next time you see this bug? Thanks.
Jason San Jose
Quality Engineer, Flash Builder