You do not need to close out the work stations. It is using the data over the network so as long as the server is closed out, any workstations should be able to connect to it.
The two most common things that will cause the error you are getting is the date on the computer being wrong or most commonly a network issue. First thing I would suggest is going into "My Computer" and make sure the work station can see the mapped drive to the server.
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Robert
Wise Software Tech Support
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