STRANGE! HELP! Why is this happening to my buttons

Ok, See the attached images, and storyline file

I have a three button tab page.  When a button is clicked, a layer is shown.  Also, the other two buttons are set to 'Disabled'.  When the timeline ends on the layer that was selected is finished,  a trigger has the two disabled buttons set to Normal again.  

BUT, when selecting the next button, the formatting on the previously selected button goes haywire! 

Why is this happening?!?!?

Images below:

The un-selected initial state of the buttons.  

The initial state of the buttons, nothing selected:

One button selected and layer showing...

Lastly -HERE IS THE PROBLEM!

And running  the page again resulted in this strange look!