Transition/timing becomes rapid, then white or stops cycling

I’m having some issues.

In Chrome & Firefox (Windows 7): Sometimes it works perfectly and correctly cycles through the images in order. Then other times I get the flickering images or it stops cycling for a long period of time. And sometimes there’s no image at all.

Checked it on an iPhone (Safari) … I’m getting an error after a few minutes. “A problem occurred with this webpage so it was reloaded.” After that is when the issues begin. I reload the page and get the same error and images flicker when transitioning and then stops for a time. Or just freezes and then I get the error again.

Do you have any ideas what could fix these issues?

Thanks.