Rollover Slidelets behave differently when they appear later.

I've got several slides in my non-responsive project that use rollover slidelets so that when users hover over different parts of a document screenshot, the title of that section appears on the slide, and when they click it, they're taken to the corresponding explanation slide. The image and slidelets are identical on each slide, and I've got two problems. The second one seems to stem from the solution to the first. 

1. The rollover area causes any animations to pause (but not my sound), leading to audio desync and weird entry animations. 
To solve this, I told captivate not to display the slidelet areas until after the animations are complete, so it won't interfere. However, that led to 

2. Now the slidelets always appear with a little white box with an "x" in the upper right hand corner, as pictured here: 

This only happens on slides where the rollover slidelets are not displayed for the entire slide. If they load with the slide, that X doesn't appear. 

Anyone know what causes this, and how I can get rid of that X? OR, is there a reasonable alternative to the rollover slidelets to accomplish this? I don't need HTML5 or responsiveness for this particular project. 

Thanks!