Please paste the exact error message that you're receiving, that way we can be more certain what is going on. You may also like to include what connection to the Internet you're using, your Operating System, the network you're using and your mIRC version.
Before going any further however, make sure you have read
this thread and make sure you use the
search feature to see if the question has been answered before (which is more than likely). Search 'All Forums' and the 'Entire phrase' and search in 'All posts' for maximum results.
Regards,