An employee when accessing his email through Outlook Web Access has to authenticate frequently with the Exchange server. This frequent request for authentication takes place while he has logged in OWA, while drafting, sending and replying to email. The employee has been accessing OWA for years with out incident. The employee has used another computer to access OWA, draft, send and reply to email with same result of frequent authetication request with the Exchange server. Do you have any suggestions to trouble shoot the matter would be appreciated.