Every 10 seconds the CPU load spikes to about 40%--even when I am doing nothing. Worse, any letter I was typing when it happened gets doubled, so I endd up with sentences likke this. A system monitor like "top" shows that X is the program hogging the CPU, so I can't kill it. The spikes are very regular, so I thought it might be some kind of daemon.

This only happens in KDE. I don't have the same problem in Gnome. It happens with most programs, but not all (as far as I can tell). Here is a partial list:

showimg (KDE-based file viewer): NO
the GIMP 2.0: NO
gkrellm (system monitor): NO (it's always on)
Quanta + (html editor): YES
KWrite: YES
Konsole (terminal program): YES
Galeon (GNOME-based web browser): YES
Konquerer: YES
Mozilla: YES

What's more, if the programs are minimized, they don't cause the problem. However, if they are maximized, covering them up by a well-behaved program doesn't fix it.

Based on one suggestion, I tried changing to the generic VESA driver instead of a card-specific one. That helped (the CPU spikes were much less), but only worked at 60Hz, so the flickering caused an instant headache.

I posted this a while ago, and most people suggested upgrading KDE, so I did. Didn't help.
Some people guessed that it was a problem with fam, so I tried killing it. Didn't help.

System:
Mandrake 10.0
KDE 3.3
ATI Rage 128 video card (yeah it's old, but I don't need anything better)

---Dan