Please, I am getting crazy with the pagination class :(

[eluser]Althalos[/eluser]
I'm not a pro myself, but my guess is that it would work if you would put $config['base_url'] = site_url('articles/index');

I can see two things that could go wrong when you put $config['base_url'] = site_url('articles');

1) The pagination class looks up the third URI segment by default. In your case, the page number would actually be second segment
2) The second segment normally is the method. So if you link to example.com/articles/2 instead of interpreting that as page two, it might look for a method called 2 and this might be what causes the 404.