cpu constantly busy on debian sid without doing anything...

[Dietrich Bollmann <diresu@web.de>]

Since some time the two cpu's of my system (Debian sid running on a
thinkpad laptop x60s) are constantly busy up to the point that even the
key-repeat (pushing down some key for repetitious input) doesn't work
anymore when using an external usb keyboard.

the system monitor shows for example:

CPU History: ... cpu1 76.2%, CPU2 77.8%

and using top I find:

Cpu(s): 70.3%us, 5.4%sy, 0.0%ni, 21.6%id, 0.0%wa, 0.0%hi, 2.7%si, 0.0%st

but no busy processes are listed (Xorg: 4% cpu, gnome-system-monitor 3%
cpu, hald 1%cpu, epiphany-browse 1%cpu, top 1%cpu, mysqld 0%cpu...)

I wouldn't mind so much if I still could use crtr-h, ctrl-f, ctrl-n, ...
normally in my emacs.  But for the moment even editing a simple text
file is a pain because of key-repeat being so slow :( 

Any idea what could be the reason?

Thanks, Dietrich