http://www.microsoft.com/communities...=en-us&m=1&p=1
First thing to try. Log in to OWA and click Options. Scroll down to E-mail
Security and click the button to install the latest version of the S/MIME
control. If you don't see that, or if doing that doesn't resolve the
problem, proceed to the next paragraph.
Your Exchange
server is not up to date with all hot fixes. The following KB
article describes and links to the hotfix that needs to be applied to the
Exchange server in order for OWA to work properly with IE7.
The Compose Message form stops responding after you install Internet
Explorer 7.0 and the S/MIME control on an Outlook Web Access client in
Exchange Server 2003
The Compose Message form stops responding after you install Internet Explorer 7.0 and the S/MIME control on an Outlook Web Access client in Exchange Server 2003
Direct link to the page with the hotfix -
Download details: Update for Exchange Server 2003 SP2 (KB 924334).