I don't think I'm meant to play this game. It worked fine up until now, and I've done nothing to change my computer settings or anything. I played this only a few hours ago, and now whenever I load the game, the cursor leaves a copy of itself wherever I click, and when I finally get into the game after loading my last save, it gets even worse, it leaves a trail of flickering cursors everywhere on the menus (not in the game window for some reason).

I tried using the nvidia fix, but whenever I tried to run it, it says I don't need to use it.

If anyone wonders how my install looks like, this is the exact guide I followed:

http://www.gog.com/en/forum/baldur_s_gate/baldurs_gate_2_essential_mods

Minus the optionals.

I'm running Vista 64.

It's a common problem. Not sure about the exact fix (I think it varies from computer to computer), but you can either try turning off hardware acceleration or try what's suggested in this post: http://www.gog.com/en/forum/baldur_s_gate/mouse_flickering_across_screen_leaving_trail_in_full_screen/post5