* Unable to connect to server (Permission denied)

I know there are a lot of posts about not being able to connect but I've only found one other person with the error message (Permission Denied) on trying to connect, and that was on mIRC forums and had no answer. No one has been able to tell me what causes it and how to fix it. It's a new problem, I have been able to connect to Undernet for years and as far as I'm aware I haven't changed anything. I've tried every Undernet server I can find (http://www.undernet.org/servers.php and mirchelp-undernet.org/servers.html) and on all available ports with the same results. I've tried a fresh install of mIRC which didn't work. I can connect to other networks (Quakenet, DALnet etc) fine. I've tried temporarily disabling my firewall. I've tried DNS look up and then connecting to the IP address of servers. I've tried changing the look up method between Normal and Server etc. I can connect to Undernet with a web based client (mibbit.com) and another computer on my network using the same internet connection is able to connect.

I have no idea what's gone wrong. Any ideas would be greatly appreciated.
Thanks peoples.

Turns out Permission Denied is a socket error (10013) I chatted to Collective in #mIRC who told me to reset winsock, which allowed me to connect, but I only stayed connected for about 60 seconds. After that I would get (Permission denied) again.

After trying everything anyone could think of, checking all the right ports were open in the router, making sure I had a static IP address for my machine and pulling my hair out, I finally decided to give up and resort to reinstalling windows. I didn't have enough time to do it for a couple of days and left mibbit connected to IRC in my browser. I sat down tonight to reinstall windows and I had a message from Collective suggesting that it could be MALWAREBYTES blocking the connection. Something messed up and it didn't uninstall properly the first time but when I rebooted mIRC connected and stayed connected!

Thanks #mIRC, Collective, Eenie and CaptainGizmo!