Why Can’t we see our Web Page?

I administer the web page for a small city. Recenly our web provider made changes to his web server, which resulted in our haveing to totally reload our web page. This went well except that now the city computers do not see the current web page (except for one computer). Other computers outside the cityhall have no trouble getting the latest update of the web page but we can’t. Calls to the web provider have not shed any light on the problem. Does anyone have any idea?