You might be able to use the same line of code setting the enabled value to true. If you have not locked the root of the loaded swf, the _root should till be pointing at the main movie.
_root.intro_btn.enabled = true;
Yeah that was my first instinct.
I tried that but for I think the _root ref from the SecondMovie.swf is only ref _root of SecondMovie.swf and not the Movie that SecondMovie.swf has been loaded into.
Try using _level0 instead of _root.
haha I just tried that before coming back here to check for a reply.. Thanks again that worked.