I'm trying to get a symbol track the height of the mouse.
I don't want the user to have to drag the symbol, I just want it to adjust
it's height to correspond to the user's mouse pointer.

The other thing that may be a problem is that there's a particular bit of the
symbol that protrudes, a bit like an arrow... I want this bit to be exactly the
same height as the mouse pointer, maybe this can be done using action script
and saying the symbol heght -50 pixels (for example) = mouse height.

Does anyone know where to get this script?

mouseTrackI=setInterval(mouseTrackF,40);
function mouseTrackF(){
yourtrackerMC._y=_ymouse; // you may need to add or subract a fudge factor
depending upon yourtrackerMC's registration point and your personal preferences.
}