Special character just on part of the site.

Hi,
I have latest version of OC (2.0.1.0) installed and I'm making my own translation of the front end of the site to spanish. I started with the first folders and files inside language folder. As I'm translating files I upload them and check how they look. The funny part is that all special characters like á, í, or ñ looked fine until I reached "checkout" folder which, in the front end, started to show � instead of original characters.

Is this ok or a bug? Should I replace everywhere special characters like "í" with í and so on or is there something I can do to avoid that? Howcome they show fine in part of the site and don't in other parts?

Thanks a lot!

Edit: sorry, I think I posted in the wrong section. This should be in 2.0 support.