Thank you for responding! The situation has been getting worse,
and my family is beginning to mutter about PCLOS... (My son thinks
the system has a virus!)
Here is the kde version info:
$ kde4-config -v
Qt: 4.8.2
KDE Development Platform: 4.9.2
kde4-config: 1.0
I have been keeping Synaptic up to date, I believe my problems started when I went to 4.8
(the BIG change that required extra steps).
After a boot the system seems just fine, but over time bad things start to happen,
and unfortunately I have no idea what I might have done to trigger them.
Some of the phenomena which happen to me: (in no particular order)
* my keyboard layouts still work, but the kde layout indicator on the panel gets stuck showing
the current layout.
a) clicking it has no effect (clicking usually changes layout)
b) changing layout is not reflected in the indicator
* apps that don't start at all, or take VERY long. e.g. clicking to start Dolphin from the panel, I see it starting up,
then its icon vanishes, and Dolphin "suddenly" appears on my screen about a minute or more later.
* In the Dolphin window, a right click hangs Dolphin, and no menu appears. Some time later, I might be in
a different app (e.g. firefox), on a different desktop, and suddenly up pops a Dolphin right click menu.
* In a konsole, I try to select some text with the mouse, but there is no sign of a selection happening.
The konsole window becomes stuck - if I move to a different window and then return, the konsole window
does not redraw itself.
* I leave my user locked in screensaver, and a different family member uses the computer, by clicking
"Switch user" and "Start new session". Later, when I log back in, I find the image of the
"Start new session" window stuck on top of my desktop! I cant use my running programs unless I can
move them around to the part of the screen not covered by it. I don't know how to reinitialize my
desktop other than logging out and in again.

* Attempting to log out does not always work. I have been stuck both with the Lock/Logout widget
on the panel, and with Start/Leave/Log out. The desktop becomes stuck, but the user remains logged in.
I have gone to tty1 and killed startkde to get out of that situation.
* Logging in again after I logged out because of problems doesn't always help. When my user starts
up, I see that some things are not working, particularly klipper and kmix in the panel.
* I have also noticed that even when I am supposedly logged out, some tasks of mine remain in the system,
I particularly remember gam_server, gpg-agent, and one or more copies of: kdeinit4: kded4 [kdeinit]
You asked about error messages. No, I did not see anything out of the ordinary, AFAIR.
Before starting dolphin from konsole to see any Dolphin messages, I just now closed an open Dolphin window.
It gave me this:
We are sorry, Dolphin closed unexpectedly.
... etc...
Details:
Executable: kdeinit4 PID: 4258 Signal: Segmentation fault (11)
(I have not seen this recently, it's a first).
Here is what I got starting it on konsole (but right now the system is behaving beautifully!! :-))) )
$ dolphin
"/usr/bin/dolphin(27371)" Soprano: "Could not connect to server at /home/shimon/tmp/ksocket-shimon/nepomuk-socket (No such file or directory)"
"/usr/bin/dolphin(27371)" Soprano: "Could not connect to server at /home/shimon/tmp/ksocket-shimon/nepomuk-socket (No such file or directory)"
dolphin(27371) KSambaSharePrivate::testparmParamValue: We got some errors while running testparm "Load smb config files from /etc/samba/smb.conf
Loaded services file OK.
Warning: Service printers defines a print command, but rameter is ignored when using CUPS libraries.
"
Thank you VERY much,
Shimon