This is always a sensitive question: Do you have the real game or a copied version? I hope you realize copy protection won't let you play with a copied version.
In other cases, I'd try downloading the patch if you haven't done that already. I heard some people who had their game running fine after installing the latest patch. Unfortunately, the support section of Larian is currently down until the 1.42 version of the patch is released, which should be later today.
Tovi 
