Click sound when there should be no click sound

Good morning. I hope you all enjoyed the holidays : )

I am having a fun problem in Internet Explorer 11 (but not with current versions of Chrome and Safari) with my Captivate project. 

Part of my navigation are two buttons -- one has the action "Jump to next slide", the other "jump to prev slide". Simple. The click sound is deactivated for both and the they are set up to show for the entire slide.   The problem: on some slides (while playing project on IE), you hear a click sound when clicking these buttons, and sometimes you even hear the double-click sound.  It's always the same slides this happens too, but it doesnt happen on these slides all of the time, only most of the time.

The "infected" slides are part of a software simulation and some of them have the mouse element on it, and some have the mouse removed. There is typically another shape or label explaining what it going on as well. Other than that the slides are pretty plain...

Any ideas what could be cause this problem in IE?

Thanks for any help.