Vista - Debugging or even running a script in MSE7

I just ran across MS Script Editor - it's been on my machine forever, I
guess, but I only recently found it and am trying to write a new VBS in it
instead of Notepad. But I'm having trouble getting past the first step: I
installed the debugging part, but when I try F5 or any other command to run
my sample script, which consists of a MsgBox and nothing else (except
comments), it just switches to Run mode for a few seconds, then back to
Design. I can get the MsgBox text when I run it in other ways, but not via
MSE7.

So is there something particular I have to do? I see something about
"loading a script to a process", but I'm not sure what that means...?