Assassins Creed 2 internet connection error?

[ThereIsAHellBelieveMeIveSeenIt.]

So I bought the game, installed it on my computer, and whenever I try to play it, it tells me that an internet connection is required and that I have to check that my internet it switched on. Of course, I have constant internet connection, and is always turned on.

So why is this error popping up?
And what can I do to fix it? I spent a lot of money on this game, and I'm not going to let it go to waste.

I'm not a computery person, but I can do basic stuff, so if you have a solution, can you please explain it in the easiest words possible. Thanks.
My computer most defiantly has the minimum system requirements, if this helps.