I had been using Notes admin quite happily on my Win NT machine registering people on two different domains. However, I decided to upgrade to Win2000 and now when I try to register people on one of the domains it doesn't let me, saying that there are duplicate names lready in the address book. I have read articles relating to this (basically saying that the server has to be running a similar OS - or something like that) but not seem to relate. I have a colleague who did exactly the same and his machine works fine. Does anyone have any clues as to what this may be. Lamaar75@hotmail.com