I have tested the plugin in various environments and there is a problem with the next and previous buttons in the latest versions of Chrome and Firefox in Windows 8. The plugin works in the exact same browsers in earlier Windows versions.
<a href="#">Next</a> and
<a href="#">Previous</a> buttons the browser window jumps to the top and the anchor tag # is added to the url in the browser location bar. The only image that is shown is the first image in the post gallery. The behaviour can be avoided by adding onClick="return false", but then nothing happens when clicking next or previous.
Strangely I cannot reproduce the error in Internet Explorer in Windows 8 or in earlier Windows versions in any browser.