This solves also my problem under Ubuntu 8.04 (Long time suport) version:
In 8.04 add under [X-:*-Core] in the file "/etc/kde3/kdm/kdmrc" the following line: TerminateServer=true
In KDE 3 there is no line to comment out, so you 've to add this line. I see X and kdm restarting at logout.
This solves also my problem under Ubuntu 8.04 (Long time suport) version:
In 8.04 add under [X-:*-Core] in the file "/etc/kde3/ kdm/kdmrc" the following line: =true
TerminateServer
In KDE 3 there is no line to comment out, so you 've to add this line. I see X and kdm restarting at logout.