I have Exchange Server 2007 running on Windows 2008. I've been using Outlook Web Access with a purchased SSL certificate for a couple of months now. It has been working fine. A few days ago it stopped working. After a couple hours of messing around, I found that I could still access OWA via the non-secure http site. However, when using https, the browser just says it can't open the page and no activity shows up in the IIS logs on the server.
I had rebooted the server about three or four hours before this problem developed - which initially made me think some service wasn't working. Looking at the IIS logs, I found that a user had sucessfully used OWA a couple of hours after I had rebooted though.
I can't find anything in the Event logs - other than an Exchange error regarding certificates and STARTTLS (or something like that), but those messages date back well before the problem.
I also turned off the server firewall for a few moments to make sure it wasn't a firewall issue.
I'm not sure where to look next.