The only way that could be done is with a trojan/backdoor/virus. In other words, you got it from something you downloaded/opened/from going to an infected website. Thats why we strongly recommend using caution in downloading, opening emails, typing whatever someone tells you to, clicking on every url thats spammed. Using a good virus scanner and keeping it updated helps, but isnt a complete solution. (and yes, server.ini as opposed to serverS.ini is a common nasty).
I suggest a good virus scan or two. Try this free online one here
as it catches some IRC things others miss. Make a note of what it finds, and use the research that site provides to be sure you dont have to manually do some further editing