>It was within literally 10 minutes when the customer sent me email saying that they check everything, as far as firewall or AV and were still getting error. And then I started the SQL Server Browser service and asked him to try again. And he said "everything works now." It is, of course, possible that something else may have occurred at the same time. But I don't know.

When the server was restarted, was it still running? Or, when that PC was restarted, was is still running?