bug#1687: Emacs.app -- Warning: desktop file appears to be in use by PID 537.

[Adrian Robert]

> If I choose "Quit Emacs" from the "Emacs" menu, the next time I  
> start up
> Emacs, I get a warning of the form: Warning: desktop file appears  
> to be in
> use by PID 537.  Furthermore, if I then try to send a bug report,  
> Emacs.app
> freezes after I enter the above as subject of the bug report.

I can't reproduce this here on 2009/01/21.  How are you starting  
Emacs in these cases?