Expansion Pack Confusion

[HighElfSorceress]

So I am having a bit of trouble. I just beat Shadows of Amn, so I decided to install Throne of Bhaal to continue my adventure and whatnot. I am unfamiliar with expansion packs; I've only used one once before, about four years ago. So I'm not completely sure what I'm doing. But I put the disc in (my discs are also mislabeled, making everything wonderfully confusing) and the Throne of Bhaal launcher came up, so I clicked Install and went through the whole process. I'm pretty sure I did a full install, not the minimum (though I'm not sure if SoA was full or minimum if that makes a difference). Then I ran the game.
It got me to the screen where it asks you to choose if you want to run SoA or ToB, and I clicked ToB, and it said like "Error: No disc in drive. Insert expansion CD" or something to that extent. I opened the disc drive and checked to make sure I had the right disc, since with the mislabeled thing it was very possible that I screwed it up. Nope, it was definitely ToB (which is labeled as SoA because logic), so I put it back in and nothing happened. I thought maybe I had a memory problem and that they weren't mislabeled and I was going insane, so I put the other one in. Nothing. Then I pressed Alt + F4 to close out and it had the whole spazzy thing where you have to go to Task Manager to completely close out, but I think it always does that.
I rebooted the computer and did the whole process over again, twice. I even tried showing it to my dad because usually when I make a huge deal out of something not working then make him come in and look at it, it'll start working again and he'll think I'm crazy, but that didn't happen.
So now I am confused. I looked at a ton of help forums and didn't find people having the exact same problem, and people with similar problems had all different responses that didn't make sense. So I was gonna uninstall, but I was afraid that something would happen to the other saves (my brothers both play the game too and they haven't beaten it yet, so I don't want to screw up their saves). I would back them up, but their saves are not on my user and I can't access them. So I figured I'd wait until I can back them up, and post this thread in the meantime to see if anyone has a solution.
So, if you have had a similar problem and solved it, or you just know how to because you're magical like that, I'd appreciate all the help I can get. Thanks in advance!

[swcarter]

If you have an actual, legal copy of the game, then I'd suggest uninstalling and reinstalling everything. If you don't have a legal copy of the game, then I'd suggest buying one, since you can get a BG2 bundle for less than $10 now.

SWC