KMail keeps starting "standalone"

[Derek Broughton]

When I shut dowm, I usually leave Kontact up and Kontact is set to open Mail
as the default application.  

In the last few days, every time I log in KMail starts up as standalone,
even though it was not started when I shut down.  Then Kontact starts up,
and when I try to switch from News to Mail, a message appears in the status
bar something like "Application was started standalone.  Foregrounding."

I've got nothing in my .kde/Autostart folder to start KMail.  Any idea why
it would start itself?  I had changed some Kontact config settings shortly
before this behaviour started but I can't see that I changed anything that
would cause this.
-- 
derek