Hi there trytux!
We have an article online that can tell you a little about kernel panics on your machine, and can even help you troubleshoot the issue. That article can be found right here:
Hope that helps to inform you a little more about what may be happening on your computer. Thanks for coming to the Apple Support Communities!
Thanks, for the info (and links).
After some research i did also a test with a Linux-LiveCD from which i booted the MB. There i connected a device to the FireWire Port and as expected i got error-messages about the FireWire port, it wasn´t a kernel panic this time. It looks like the FireWire Port has a hardware failure and i guess reapair it isn´t worth it...