Are you running any scripts? If so then install a copy of Plain Jane mIRC and try with that. Don't use proxies or BNC, make sure your firewall allows the port you want to connect to the server with, make sure you are using ports your chosen network will allow - when in doubt use 6667 as it is generally the most accepted one. Make sure you set mIRC to attempt to connect for long enough, 30 seconds should be enough though if you cannot connect within two minutes then you really do have a problem. This sounds odd but maybe your ISP doesn't allow IRC? Ring their helpdesk and make sure they do. That's all I can think of at the moment.
