After a while, dolphin, konqueror (and other KDE apps) won't start...

[Steven P. Ulrick]

Hello Everyone,
I am running KDE 4.7.3 on a fully updated fresh install (not an upgrade) 
of Fedora 16.  If it is relevant, I am running an NVidia based video 
card with the default open source Nouveau driver.  Also, the problem I 
am about to describe occurs when I am running a full KDE session, not 
when I am attempting to run KDE applications from GNOME or some other DE...

My problem is pretty simple: after being logged into a KDE session for a 
while, for reasons that I have not yet narrowed down, I am no longer 
able to start at least the following applications:
Dolphin
Konqueror
Kwrite
Kate
Ksysguard
(There may be others...)

Let's say I login to a fresh KDE session.  All of the above listed 
applications start and function perfectly.  Then, let's say I have 
closed all instances of the "offending" KDE applications.  If I attempt 
to start one of them from KRunner, it just does not start.  No error 
message, nothing to indicate WHY it did not start.  If I try running one 
of the above listed applciations from a terminal to see any error 
messages that will be displayed, absolutely NOTHING is displayed on the 
terminal.  For example, if Dolphin won't start, and I attempt to start 
it from a terminal, it will look exactly like this:
steve at localhost ~$ dolphin

No output whatsoever...

I think that I can start Konsole just fine when those other apps won't 
start.  Next time this problem starts up, I will make sure.  But I do 
|remember trying to start Dolphin from Konsole last night, with results 
like those shown above.  So I'm pretty sure that Konsole is not affected 
by this.

Also, I THINK that this might be related: when I try to log out of KDE 
when this problem is occurring, it just silently fails.  Translation, I 
attempt to log out (using "Kickoff Application Launcher | Leave | Log 
out" and nothing happens.  So, I do "Ctrl | Alt | Backspace" (which does 
take me out of the KDE session and to the login screen) and attempt to 
log back in.  The KDE splash screen comes up, but it seems to hang on 
the first icon (the one that looks like a harddrive/disc drive of some 
sort.)  If I reboot, I can log into KDE perfectly.

So any help you can give me is greatly appreciated.

Steven P. Ulrick