Well, I'm not an expert, but did you check if you have these lines in your baldur.ini file:
HD0:=D:\Games\BGII - SoA\
CD1:=D:\Games\BGII - SoA\English\;D:\Games\BGII - SoA\CD1\
CD2:=D:\Games\BGII - SoA\CD2\;D:\Games\BGII - SoA\English\;D:\Games\BGII - SoA\CD2\
CD3:=D:\Games\BGII - SoA\English\;D:\Games\BGII - SoA\CD3\
CD4:=D:\Games\BGII - SoA\English\;D:\Games\BGII - SoA\CD4\
CD5:=D:\Games\BGII - SoA\CD5\
The paths will of course differ dependent on where you have the game installed.