Mouseover woes....rollovers stick and won't mouseout

I've used this method before but this time around, it's not working for me. The files are at:

https://www.dropbox.com/s/ccgapo20p233h7z/rollover.zip

Basically, there's a navbar on the top right. It's very simple. Six symbols. Each one has a half second animation of the black box fading in from 0 to 100%. Stop actions on 0 and half a second. Have this on the root for each button on mouseOver:

var myBtnExploration = sym.getSymbol("btnExploration");

myBtnExploration.play();

and for mouseOut:

var myBtnExploration = sym.getSymbol("btnExploration");

myBtnExploration.playReverse();

of course, the references to the symbols are different for each button. Nothing crazy.

So what's happening at times is you rollover the first button you select (doesn't matter which) and the effect is fine. Anything after that and who knows. Usually it sticks on the rollover state on mouseOut. Anyone know why this is happening and what the fix might be?