My friend gifted me the GOTY editon on Steam and after installing it I've noticed some problems, some were fixed, but this one remains.
I've searched over 2 hours on forums and Google and such, never found a topic similar.
I really need help on this:

Whenever I'm in the game, whatever the resolution or the aspect ratio, matching or not, fullscreen or not, the cursor will be limited and will not go in corners and edges of the screen, just like if it was on a smaller resolution by itself.

Let's say there's a button on the bottom right corner of the screen. To reach it, I will need to align my cursor more in the center, in other words i'll have to find the actual spot where the cursor will click the button because when I hover over the button it doesn't click it at all, just like if it was miscalibrated.

i never got this problem in any other games I had, if that can help.

I don't need to post my specs, I am certain it has nothing to do with graphic cards, processors or RAM. But If it helps, I have Vista SP2.

I BADLY need help on this as I'm going on a trip tomorrow and I want to have a game I can play offline without many troubles.

Thanks for understanding.
Please help me :C