Today my brother was telling me that OmnomIRC didn't work for him, and it wasn't the cache.
So I went to look for the problem, and here is what I found:
Inside the code their is a line which converts your username to base64, and it looks like this with me:
userName = base64.encode("jimbauwens");
However, with Stefan (nick is "Stefan Bauwens"), it looks like this:
userName = base64.encode("Stefan
Bauwens");
It is divided over 2 lines. This is probably because the space in his name gets somehow replaced with a new line.