[SixOfSpades]

Okay, this sounds like a really funky one.
1) Crashing upon entering a map area usually means that the *.BIF file for that area is corrupted. Since reinstalling didn't help, you've got good odds of having a scratched CD.
2) Why the hell it's talking about C++ is beyond me. Do you have some C++ program running in the background or something?
3) "...when I tried to transfer my save to another computer, it said the disk wasn't formatted." Try transferring some other form of data, in the exact same way. If it only screws up when trying to copy your game, then congratulations, you've got a corrupt Save file.
4) How many (non-bugged) games of BG have you played previously? Have you seen this problem before?

Possible Solutions:
Go around that particular map area, or reinstall the game using some OTHER set of discs.
Since this is so early in the game ("the city that Jaheira wants me to go to" = Nashkel, yes?), then you could just delete the damn thing and start from scratch.