Version: (using KDE 3.5.9)
Installed from: SuSE RPMs
Kontact should be smarter with displaying this message. It is displayed quite often on my computer and the kontact is in fact not running at the time. Today my KDE - don't know why - started kontact twice and after clicking on start in the message dialog I had two running kontact instances. Kontact should rather detect if it runs by the means of process list or a socket.
One case I noticed the message occurs is probably after kmail component crash. This probably invokes the message on the next start.
*** This bug has been marked as a duplicate of bug 185544 ***