I'm having this same issue. I've read through this thread and tried everything I can, but nothing is working.

For me, I connect for about half a second before I'm disconnected. It's not like I'm in the middle of chatting, and boom I'm gone. I never get to the chatting part.

I have to assume my problem is my school. I just came back this past weekend, and mIRC isn't working. It's been working fine all summer, and even last semester at this same school.

And advice?