I have just installed Packet Builder (build 149) and the program fails to detect a network adaptor. None are listed in the selection drop down list. I have also tried an earlier version (138 ) without success. Both packet player and MAC scanner tools on the same PC have no such problems and the adaptors are listed. PC: Asus P5B (integrated Realtek RTL8168/8111 PCI-E Gigabit Ethernet NIC) Intel Core2Duo E6750 2GB Crucial PC6400 WinXP Pro SP2 Strangely, an identical PC (hardware wise) running Vista works. I've copied over the working folder from this PC to the Win XP one but still no joy. Is there a registry setting I can edit? I've looked but could not find one. Thanks. Update: I've now tried this on my company laptop, also WinXP SP2 and I get the same problem. Is this application broken on XP?? I get the error message box 'Not find adaptor' on both XP PC's. I did find a regisitry entry for default adaptor, but it was empty. I added in the keys from the Vista PC and edited the driver path but I still cold not get it to work.