Version: 1.8 (using KDE 3.4.0 Level "a" , SUSE 9.2 UNSUPPORTED) Compiler: gcc version 3.3.4 (pre 3.3.5 20040809) OS: Linux (i686) release 2.6.8-24.11-default Start kontact, shut down computer (probably it suffices to shut down kontact, but I did not try), start computer but use another hostname, start kontact again. As a consequence, I get the error message that kmail seems to be already running, and it does not react on a button press, i.e. I have to kill it. The only way to start kontact again is to remove the lock file $HOME/.kde/share/apps/kmail/lock by hand. It seems that the reason for this behaviour is that the hostname is stored in the lock file.
I can confirm you cannot click on either button on the dialog. You can only click the X to close the window, which leads to kontact exiting. Another thing is that the lock file should be removed if kontact/kmail receive a signal, like SIGTERM. Finally, the fact that you changed the hostname makes this all the more difficult and I'm guessing that part is a WONTFIX.
This bug does not appear anymore in kmail 1.8.1