Back on topic: I think that the Dot TK's service can be the cause. I've read lots of user reviews, and from what I see, they can delete the domain if it gets too much traffic (like more than 500 users a day), without any notification, etc. This shows that there is no reason for me to stay on their crappy service anymore. I hope, however, that I will at least manage to restore it to get the links working, or that it could have a redirect.