If you have access to a server that is publishing datasources, and that server is either started or stopped during your session, then right-clicking the ProjectWise Explorer Datasources item at the top of the datasource list will either add or remove that server's datasource(s) from the datasource list accordingly. Refreshing the datasource list will also add any new datasources that have been created (on servers you have access to) after you have already opened ProjectWise Explorer, and it will remove from display datasources which you have been restricted access to.