While there may be other issues such as antivirus suite interference a thing I try is to go to ninite.com and check off itunes there and run the installer it provides. Why ninite.com? Read
Why not use Apple.com? We are trying an alternative quick fix before we go to the Apple Itunes Forums at https://discussions.apple.com/community/itunes/itunes_for_windows
Has anyone had this problem? All was working well until the latest Itunes update about a week ago. Now, "nada"!