OWA Not Responding + Different Server

Outlook web access is installed on a web server, with Exchange 5.5 sat on the mail server. the problem has arisen where accessing e-mail remotely causes the OWA to hang as the mail has previously been accessed via Outlook2003. The fix has been applied to the Exchange server as per Microsofts hotfix ( http://support.microsoft.com/default.aspx?scid=kb;en-us;818709) however the problem still occurs. The OWA access being installed on a different server (without exchange) means that the patch can’t be applied to it.

Any ideas?