First and foremost, I have looked for solutions to this for some time now, here on the mIRC boards, and on other sources. I've configured my router to allow all the ports mIRC uses, including 6667-6669, and 113, with no luck. I've enabled the ports necessary, and then disabled the Windows Firewall as well.
Oddly enough, another computer on my network, behind the same router, can connect with no problem.

No server/network combination seems to work with mIRC. I've reinstalled the client several times as well.

I'm out of ideas. Any help?