I have a problem with my Excel 2000.  Three of my users are working on the Same Excel document which is saved on one computer.  Can they access this document at the same time and edit it from different computers and save the changes.  Or is it only possible to save the changes on the main computer only and the others have a read only permission?  Now whenever I try to save the changes from a second computer, I receive an error message and it does not save. Can anybody help me?