Hello Nathan, 

Have you tried a different browser or a different connection/computer? I tried reproducing on my machine and was not able to see a problem with image loads or the slider upon multiple refresh.

Typically when images have issues loading intermittently it has to do with your browser or connection breaking mid page-load. There also may be a conflict with some of the other scripts you are running on the page, if you take a look at your error console there are a few in there. As a side note it looks like the script placed at the bottom of the site is overlapping with the footer. 

Thanks.