Rehi, for thos interested:I temp. fixed the error by upgrading to a 2.4.13, but one day later the problem arraised again. I tried to manually force the slots to specific interrupts, but no mater how i did it, my AGP card and the NIC shared the same IRQ. So the solution was quite easy: i put the NIC into another slot and... bingo! Everything works fine now.
Timo