I`ve installed the games on the D: partition - they`re both patched. I have the Polish 1 DVD "Saga Baldur`s Gate" edition. 25movies.bif is in the "D:\bgII SoA\Movies" folder.
I had this too few days ago, and I say it's a faulty baldur.ini file in your game folder is, so open the file with Notepad and make sure the file has the correct patch to all the [Alias]'es... like so:
Remember to remove the extra paths. And make the last Alias have two paths, 1 for the game file(D:drive), and one to the CD/CD-image drive(G:Drive in the example). Of course this might be more complicated if you have non English game as the language might need to have some extra path.
PS: you should really have the " - " in between the 'BGII' and 'SoA'.
I too am having this error message, but your remedy didn't seem to work for me. I've double-checked all the .ini stuff and it seems to be correct, tried it with and without the separate directing to the CD drive on the last alias... Any other thoughts on what might fix this? I don't think I forgot a \, unless I'm stupid and have misunderstood where they're supposed to go.