this script has a window.onload = function which is likely to **** any jquery $(document).ready etc functionality defined previously. it's also not using jquery at all so its not the best choice here (even though it's coded well enough and as a class..)
anyway, try to remove from the js:
window.onload = fadeshow;
and repace with:
PHP Code:
$(document).ready(function() {
fadeshow();
});
if you have an existing such function, just add fadeshow there.