Ok, thanks Bigpaws.
acpi=off did the job. However, running a laptop without powermanagement and battery-monitor isn't very funny
I think the problem is the broken DSDT-table of my laptop. I will try to append my fixed DSDT to the initrd as soon as I find the time (or as soon as I've figured out how that is done under VL).
OpenSuse 10.2 and Ubuntu 6.10 worked without fixing the DSDT. I had hoped, the improvements in the kernels acpi-system had made this a thing of the past.