For a given user on a given networked system, starting KDE (slackware 13.1 stock) hangs during the startup. CNTL+ALT+Fx gets out, and KDE / X can be shutdown with a CNTL+C, however, afterwards doing a df hangs bash.

My guess is that there is something IO oriented, as top shows a load of 9+.
There is 5% iowait according to iostat.

Ideas?

So, just to be absolutely clear, you have one user on this system, and for that user KDE hangs, other GUIs work for that user and, for the other users of this box, when they try to login to KDE, this problem does not occur.

If that is the case (and I suspect that I may have understood what you are actually saying) then renaming the .kde (or whatever slackware calls it...may be something like .kde4, assuming that we are talking kde4, of course) often does the trick, if there is something wrong with the kde settings.

It is possible that if kde makes use of the flashy desktop effects and your graphics card/driver is buggy, that can cause this kind of result, so don't rush to turn on all of the wobbly windows/zooming windows stuff straight away, but there are probably other possibilities too.

Very possibly. After a kde crash, there can be lots of disk IO going on, but I don't know how that fact helps to fix the situation...

This issue is closed.

It turns out that there were two problems. A minor one was an ethernet cable gone bad. The harder one to find was an ethernet board which did not fully reconfigure, until the host system was power cycled.

Once it power cycled, network performance improved and KDE started running normally.