Hello,
I had a look on your site, and saw the problem. I'm not a senior Javascript expert, but I think I could suggest you an easy solution. The problem with your thumbnails is that those works only with Javascript, but most JS function is initialized when the whole page is loaded. What if we hide all the thumbnails by default, and make them visible only when the page is loaded? This way noone can accidentaly click on a thumbnail a half-loaded site.
If you're interested in this kind of solution, please write me back and I provide you the .js file with the script (or additional help, if you need is). Don't pay me in advance, I'm just hunting for feedbacks. :)
Best regards,
Robert