Most likely the user's access program is opening the the database on the server in exclusive mode, to check this you need to goto the users pc, start access and open the database (any database will do) this allows you to select tools|options from the menu goto the Advanced tab on the options form an click on the shared radio button.
you may need to do this for all users installations of access, the menu's are access 97's 2000 will be similar
Robert Dwyer
rdwyer@orion-online.com.au