Running Unity off USB, Can't edit scripts. Why?

So I installed Unity and monodevelop on my USB and whenever I try to edit a script whether it be my own or a pre-built one in Unity it gives me the error:

“To run this application, you must first install one of the following versions of the .NET Framework: v4.0
Contact your application publisher for instructions about obtaining the appropriate version of the .NET Framework.”

Is there something I missed when downloading all this onto my USB?

Thanks!
-Jake

… continued from my comments.

Yes. First download Notepad++ and put it on your USB. Then see if you can run it. If you can, then you have a program that can edit scripts.

But now you cannot simply double-click in Unity to open the script. You need to do it the long way.

In Unity, right-click on the script, and select Show in Folder

Now you know where the script is. This is the Windows File Browser.

Now run Notepad++.

Now drag your script from the Windows File Browser into Notepad++. So your script should be open in there.

Make changes to your script. Now save the script.

Now go back to Unity, and watch the circle in the bottom-right corner spin around. This is Unity compiling your script. (compiling - reading your script, and storing it inside Unity in a way that Unity can understand it. This is behind the scenes stuff, don’t even think or worry about it. Your script is not being changed).

If you can edit scripts like this, and you can run Unity, then this is the way to go.

I don’t want to confuse you, so only read on if all the above is tested and working.

You can make Notepad++ your default script editor, so you can double-click on a script in Unity and it will open with Notepad++. Here is the information on how to : http://wiki.unity3d.com/index.php?title=Using_Notepad_Plus_Plus_as_a_script_editor

This is because Unity’s code editor (MonoDevelop) uses the .NET framework, which requires Windows to be installed on your USB (impossible).

A workaround would be to use Notepad, Notepadd++, or another text editor to modify your code outside of Unity, and then go into Unity so the new code is recompiled.

Just have both Unity and the editor open and Alt+Tab back and forth, just as you would with MonoDevelop.