I encountered an annoying bug (Mathematica 8.04 for Mac).
The notebook changes its name to "Untitled-1" and all the closed cells lose its information. Then I have to close it and open the last saved version, which is annoying. There is a beep but no message when this happens.
I still haven't quite figured it out how this is triggered but it may have something to do with the usage of a dynamic module. The notebook name is not altered in anyway in the entire notebook.
Did anybody of you encounter the same thing and if so how can I avoid it form happening again?