I'll try that. Not sure where, but it might not matter.

OK, added at the tail end of the other file (the one in /etc), rebooted, then logged out, and the same problem. I am resigned to just manually resetting it every time. There is something wrong here, probably having to do with my video mode or something, but unless I can find a way to execute a script on logout that will do this for me, I'm resigned to the manual method.

Unfortunate. Your best bet is likely Xsession or another similar file under /etc/X11/

I'll take a look at it. Thanks. It's not so bad that it's really a problem. I rarely logout and back in. I usually just shut down. So, not really a big thing, just a slight annoyance. Thanks.

I had this problem occasionally, but never bothered to track down a fix until now.
Adding TerminateServer=true to the [X-*-Core] section of /etc/kde4/kdm/kdmrc is not enough in all cases.
You may also have to remove pulseaudio by this command in a terminal:
sudo apt-get remove pulseaudio-*

If you do not hear a logout sound upon logout before the black screen, this will probably be the final part of the fix for you.
I tested logout after removing pulseaudio but with TerminateServer=true commented out. It did not work (black screen and monitor protesting 'out of range' so TerminateServer=true is required.

I still get a black screen sometimes after this fix but rarely (probably due to old and not well supported graphics card). Before the fix it happened every logout.

Full fix found here:
http://www.kubuntuforums.net/showthread ... 8solved%29

Very interesting. I can no longer confirm or deny the proposed "solution" because, unfortunately (or fortunately), the problem has been corrected by some automatic action (i.e. perhaps an upgrade or something else of which I am unaware).