Scratch

Unfortunately there isn't a block for that, but you can do it fairly easily. Create a variable called "Stop Sprite" or something. Right after one of your When Green Flag Clicked blocks put:

set (variable) to 0

Then around every script (you can take some away later if they are messing up your project) add these blocks:

if variable = 0
(your main code)
else
stop script

Last but not least, under the when I recieve block you were talking about in your original post put this:

When I recieve (whatever)
set variable to 1

That's it. I hope I helped!