SBS2003 OWA not displaying images on external side

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http://serverfault.com – I've got an SBS 2003 server with companyweb/remote owa site. After authenticating remotely to the https:/servername/remote site, and then clicking on Use Outlook Web Access, the mail/owa site displays only limited amounts of data with Loading... displayed (see first image). This is different when viewing the site on the server itself (see second image). Different browsers will display different types of data (last screenshot is Chrome - first two are IE). I feel IIS permissions on the virtual directories is the cause, but not certain. Forms-based authentication etc is working ok etc. Any sugge (HowTos)