Very clever. Someone has come up with a way of sharing Outlook PST files. Looks like they did it by writing a new client/server MAPI provider to take care of all the shared locking. Great solution for small businesses that don't want to run a full-blown Microsoft Exchange Server. Jenny and I have this exact problem since we have a single PST file that we use for addresses and family calendar but only one of us can have it open at any one time. It hasn't got annoying enough yet to start running Exchange. A two client license plus server for Public Outlooks costs £126.55 though.