Csharp Script won't open - Roll-a-ball tutorial

Hello everyone,

I’m currently working through the Roll-A-Ball tutorial and experienced an issue at Step 3: Moving the player. At the point, when we create a script and open it to edit some player controllers, the script won’t open. Neither double-clicking, open-button or Edit script in gear menu under Inspector works.
I downloaded Visual Studio 2010 Tools for Unity and installed it, started Unity3D as administrator but nothing changed. Somewhere I read about setting Visual Studio as external editor, but I don’t know where this setting can be done nor if it’s already active.

I’m using Unity3d version 4.5.4f1 on a Windows 7 Laptop.

with kind regards
Sebastian

this 1 might help