I've had SWB running fine for a while with the 1.11 patch (Jabbas Palace). After downloading the 1.2 patch I find I also have this installation problem. When I double click the installer it says "copying files" the bar gets to just before half way and the message "unknown error" appears, and the installer quits.
Like PyROphantasie, I have also tried reinstalling the game, but it still wont work.
This is the fourth time I have downloaded the patch (from different sources) and it makes no difference.
Where am I going wrong ?