I've had the same problem running Ethereal and nmapNT on both 2k and xp, they both use the WinPcap driver only different versions. The one I use with Ethereal is the new real version and the one with nmapNT is a modified version of it. They both use the packet.dll etc. If I install one, the other util. stops working. I can't seem to have them both installed and working at the same time. I could spend more time further chasing this down, but I guess that's partly what message boards are for. Has anyone reading this gotten the both of them up and running with success at the same time?