Exch 2000 OWA takes a long time to load

I’m using OWA with Exch2K SP3, When users try to access OWA using many differnent versions of IE and Windows, the browser loads all the icons but not the messages. The status bar says done but where the messages should be displayed it just says Loading… I’ve disabled AV on the Exchange server. It does not appear to be an client AV issue either. Any Ideas???