|It might help if you tell us what "Word...will not allow the second user of the computer to save a document" means.|
Is there an error message? Does nothing happen? Does Word crash? Something else?
What actually happens when the "second user" tries to Save a document?
Just a guess...
When the "second user" is logged on, is Word set to save files in a folder that the "second user" doesn't have Write privileges for?