It turned out that /var/lib/dpkg/alternatives/x-window-manager was flawed. It caused creation of a link to /usr/bin/kwin instead of /usr/bin/kde2.
After I changed the relevant line in the above file everything was fine. :-) -- Sign the EU petition against SPAM: L I N U X .~. http://www.politik-digital.de/spam/ The Choice /V\ of a GNU /( )\ Generation ^^-^^