Do you have a router? if so, ensure that the router is configured to allow IRC connections. If you don't know how to do that, check
this site for assistance.
If you don't have a router, are you on DSL or Cable? If so, then there might be a router in your modem. Refer to the above link.
Do you get this with just one network or with all of them? If just one, then try another.
If you get this with most (or all) networks, then try reducing the number of programs that you have running, especially things like filesharing programs. Programs like that always use a lot of resources, and can prevent you from connecting by not allowing the connection information to be relayed to the server in a timeful manner.
Just a few suggestions for you to try.