When I moved to my new house I cleaned out my comp. So I started reinstalling all my old favorite games. I was suprised to see BG2 wanted CD 5 during istallation. I figured it wants ToB, which I dont have. I had it installed but either I lost it or my friend "borrowed" it.
What I dont get is how does BG2 know I used to have ToB??? Does anyone know how to get around this? I think I will format my comp (again)when I finish IWD2. Thanks in advance for any help you can give me.

It doesn't know; this is a known error. I think most people fixed it by waiting a bit after changing CDs for the computer to mount the CD information before clicking OK that you switched the CDs.