Answering myself, from the Resource Pro Kit: .................................................................. The <ControlSet00n> subkeys represent a control set for the system. The numbered ControlSet00n subkeys, such as ControlSet001 and ControlSet002, contain control sets that can be used to start and run Windows 2000. Most systems have two numbered control sets, an original and a backup copy of a control set that has been used to start the system successfully, but the system can maintain as many as four control sets. Windows 2000 maintains backup copies so that you can undo configuration changes that might otherwise prevent you from starting the system. .................................................................. So that's that, anyway. For the record, the current one in my case was number 1. -- Jean Jordaan -- technical writer -- Mosaic Software -- Zope 2.1.6 on WinNT and W2K