SFML seems extremely "finicky" when it comes to linking. If you use the wrong version of a lib, it messes up everything.
Like all C++ libraries.
If you want to make sure everything works the way you want, build your libraries yourself. That's what I did with SDL, and now I have medium sized project that doesn't depend on any DLLs. It's actually quite easy to do.
My problem with the SDL_net extension is that last time I read it, it just made no sense to me. The SFML Network extension is so much easier to use and set up.
Helios is right, recompiling would probably be the best option, I'll mess around with that later.