ubuntu - SSL connection refused

I'm getting "Connection refused" errors for some sites being served over SSL on my Ubuntu box (10.04 LTS). It doesn't affect all sites: https://github.com/, for example, loads no problem, but https://codeeval.com does not.

I've checked my firewall settings, and there are no rules affecting connection to sites over port 443. But running nmap yields the following:

$ nmap -sT -r -n -p443 codeeval.com

Starting Nmap 5.00 ( http://nmap.org ) at 2011-06-22 11:25 BST
Interesting ports on 184.72.48.116:
PORT    STATE  SERVICE
443/tcp closed https


Nmap done: 1 IP address (1 host up) scanned in 1.31 seconds

To check that it wasn't a problem with the site, I SSH'd into another computer on my local network and ran the same command, this time getting:

$ nmap -sT -r -n -p443 codeeval.com

Starting Nmap 5.00 ( http://nmap.org ) at 2011-06-22 11:37 BST
Interesting ports on 184.72.48.116:

PORT    STATE SERVICE
443/tcp open  https

Nmap done: 1 IP address (1 host up) scanned in 0.53 seconds

There's clearly something wrong with my local config, but I can't work out what might be causing it. I haven't been able to track down any meaningful log messages; the only response when I try to connect is "Connection refused."

Does anyone have any insight into what might be causing this?

Answer

Actually, I've found the solution. I followed the advice here - SSH Connection refused - which I assumed to be an unrelated problem.

Clearing the IP tables and resetting the rules fixed my problem.

EDIT - A follow up:

I've also determined what caused the problem, though I'm now looking for a long-term solution. It would seem that the changes made to my IP tables made by software called IPBlock persist even after the application process has ended. The only way I can seem to prevent this is by flushing the tables after I quit IPBlock. Does anyone have any better suggestions?