It’s because of the javascript that conflicts with the one that other javascript based plugins use (jquery or mootols or other libraries). Lightview is one of them.
Because not every plugin can be localized (used on a specific page/post only) easily, loading the javascript only at certain times can become sometimes tricky and requires further development that is not always well documented by WordPress.
However we are working on a way to localize iSlidex in a way so that it loads the scripts only when needed, however, other plugins that always load the scripts even when not needed, could prevent it from working, and there is nothing we can do about it.
You can try to edit islidex.php, where the JS is called, and comment out (by adding // before) the lines that contain .js, and try to avoid the conflict, but we cannot guarantee that the js loaded by another plugin will be enough to make iSlidex work as it should.
You will encounter the same problems with most of the sliders out there (assuming they use javascript) and other plugins that rely on javascript.
Sorry for the inconvenience!