> I did a little research. On my machine with a 32bit system and off
> kdm_greet SAK is at rest, so I have not conducted further observations.
> Much more interesting results but I watched the 64-bit machine.
>
> 1. SAK is enabled: The CPU goes to 100%.
> 2. SAK is enabled: Switching NumLock on a PS/2 keyboard causes the death
> of the keyboard - everywhere - Xorg, console. USB keyboard switching
> NumLock survive fine.
> 3. SAK is enabled: If during the time between pressing the Ctrl + Alt +
> Delete and SAK display window, I press the Escape, SAK behave strangely.
> For example, dialog Desktop Session Locked remained displayed and next
> pressing Ctrl + Alt + Delete keys were ignored. And then kdesktop_lock
> goes to 100%.
> 4. SAK is disabled: Switching NumLock on a PS/2 keyboard survive fine.
> 5. SAK is disabled: CPU goes to 20% initially, but with increasing time of
> inactivity increases to 80%.

Bug 690 is acording bugzilla fixed by patch 1e2983a. According patch 
file it's "corrected" by adding usleep(500). If it's usleep in some 
while loop (I think it's), it's more like some dirty hack, that should 
be rewritten using some blocking function...