Installed BG2 on my ASUS UL30A notebook with Windows XP SP3. Ran it the first time. Worked fine. Went to tweak the settings, turning on 3D acceleration and upping the resolution to 1024 x 768. Ran the game again. Now it's upside down. Tried to change the settings back. Still upside down. Even tried to rotate the desktop 180 degrees through my graphics driver. Still upside down.

Erm, help?

Probably you already made that search yourself, but I found out this link about your problem. No good solutions apparently, you may try win98 compatibility mode, but you probably have to disable 3D acceleration. Double check your graphics card settings.