I am unable to replicate the problems you describe in test galleries of my own so the problems may be related to the non-gallery code on your web page.
Here are a couple of things to try which may help:
Try completely clearing your browser caches to ensure that your browsers are fetching and using the most recent versions of your gallery files from your web server.
If you want to keep expandInNewPage="TRUE", try setting useFullscreenExpand="FALSE" to see if this makes a difference.
Try checking the HTML code on your web page with the W3C Markup Validation Service and fix the errors reported. (There are currently over 300 errors reported but many are duplicates of others and it should hopefully not take too long to go through the list).
Your web page loads an old version of jQuery (v1.7.2). Try upgrading this to the current stable version (v1.10.2) and update any other out-of-date external JavaScript files. (If there is a conflict between one of your web page's JavaScript files and the 'juicebox.js' file, then updating the files in question may help.)
Even if these suggestions do not completely solve your problems, it would be wise to fix the errors on your web page and update the external JavaScript files. Once these have been done, we can eliminate them from the problem.
If the problem persists, then to check for a possible conflict between one of your web page's JavaScript files and the 'juicebox.js' file, try removing all the external JavaScript files from your page to see how the gallery reacts and then reintroduce them one-by-one until you find the source of the problem.