Here's our odd situation that cropped up today....
We have a web server sitting outside our firewall using both HTTP and HTTPS. From inside our network I can browse using the HTTPS port, but not HTTP. I can browse any other server, either ours or anyone elses, with HTTP just fine, and anyone outside our network can browse to our server using HTTP (or HTTPS) also just fine.
All the servers are running Win2k and IIS. We're running RRAS using NAT as our firewall.
Telnet to port 80 inside the firewall never connects. Telnet to port 443 inside the firewall works fine. From anywhere else (in the world) outside the firewall (including the firewall itself), port 80 opens as is normal.
(The obligatory...) This worked fine yesterday and (also the obligatory) no, there is nothing that we are aware of that has changed in any of the server configurations. Again, we can browse anywhere else normally, just not this server.... but it WILL connect using HTTPS.
The server appears to be correctly configured to respond to both 80 and 443 for this particular web site.
Ok, have at it! :-)