Well, I've encountered two problems - first the "Are you sure you're using FIREFOX" one, which I fixed by switching to Flash v7. Now I'm getting the "Unable to rip MP3 null" error. Let's review:
I have FireFox 2. 0. 0. 9.
I have the latest version of Java.
I have Flash Switcher.
I have Grease Monkey with the required script.
I point the .BAT at my custom FireFox folder, and run it.
I hit Grab 'This Track'.
I get error 'Unable to locate artist and song information' error.
I get 'Unable to rip MP3 null' printout.