This problem is driving me nuts since a couple of months now. Maybe somebody knows how to help.

Problem description
If start kontact on a freshly boot system it starts as expected.

When I close kontact by e.g. klicking on the cross on the windowframe or choosing the corresponding menuentry, kontact seems to close.

Any attempt to restart kontact will fail unless I use the following command:
killall kontact && kontact

Information about my KDE:
Kontact Version 4.8.3 (Problem exists since 4.x.something)
Installed from Opensuse packages

Configured Akonadi sources
POP3
Notes
local maildir
ical resources
birthdays
invitations source (Ical based)