Seriou problem after last potato upgrade

[Burkhard Perkens-Golomb <perkens@sdm.de>]

I'm running a potato system on a Toshiba 8000 laptop.

Since an upgrade about two weeks ago I see the known "Can't enter any
letters in kdm window, only after a X restart" bug. Not so important
but annyoing.

Since the last upgrade (yesterday) KDE seems to work slower than
before (startup is slower, opening new windows, rendering HTML
...). Can't measure it but I'm quite sure.

The very serious problem: Sometimes the mouse doesn't work anymore and
no window can get focus. I see the mouse pointer, I can move it, but I
can click nothing. Keyboard works, I can walk through the
desktops with Ctrl-F1 etc., through the windows with Ctrl-Tab but no
window gets focus and accepts input. Seems to happen when the laptop
is under higher load but I'm not sure.

How can I find the reason for the lock? What can I try if the mouse
doesn't work anymore? Don't want to kill X every time.

TIA,

        Burkhard