Probs with SSL on Outlook Web Access

Hi,

I have set up an OWA server (IIS 5.0 on Win 2000) which works fine until I put on the SSL certificate – then I get the message page cannot be displayed etc etc. I have checked MS site and they say to make sure the default website is not listening on port 443 for SSL connections but as the OWA is on the default website this doesnt matter. I’ve tried changing port numbers but it doesnt work. Its definitely a problem with the certificate because the server is listening on port 443 and the packets are passing through our firewall etc. OWA works fine without the certificate but we need it to be secured! Does anybody have any idea whats going on??!