Ok I've found something out seems it's a common problem with x64 but here's the suggestion I've found.
''Go to control Panel and click onf "Local Security Setting".....click on "Software Restriction Policies"...in the right hand colum double click on "enforcement".....under this topic..."Apply software restriction policies to the following user make sure you click on "to all users except local administors"
By doing so, it allows only the administors to install things like patches and software.''
That's about it, that's really about all I can do, especially since I don't have it for PC. So I ain't never got to mess around with it, I really hope it works though. But If it don't please post back and let me know, I'd love to help you get the game working right. No man should have these problems and should be able to play through the whole game.