One of my IIS servers at work suddenly stopped responding to SSL traffic. Normal HTTP (port 80) traffic worked fine. SSL traffic over any port (the standard port 443 as well as others) would make a connection but not transfer any data.
It wasn’t a network problem, or a firewall problem, or an IIS problem. It turned out to be a problem with the Verisign certification authority certificate. Apparently this is a known problem within Microsoft and Verisign. Read about it in Microsoft’s Knowledge Base Article #834438.
The solution is easy, and is Verisign has a certificiate authority replacement Web site with all the details. You can implement the solution even if you don’t have the problem – just to be safe.