Looking at your site again I see you have a lot of JS files here and even more throughout the source:
<script src="/templates/beer/js/jquery.js" type="text/javascript"></script>
<script src="/templates/beer/js/jquery.pngfix.js" type="text/javascript"></script>
<script src="/templates/beer/js/jquery.imghover.js" type="text/javascript"></script>
<script src="/templates/beer/js/hoverIntent.js" type="text/javascript"></script>
<script src="/templates/beer/js/superfish.js" type="text/javascript"></script>
<script src="/templates/beer/js/jquery.functions.js" type="text/javascript"></script>
Most likely one of these js files is conflicting with the image slide module and causing the problem. You could try the following and it may help, open up the mod s5 image slide php file in your modules folder and look for:
$mainframe->addCustomHeadTag('<script language="javascript" type="text/javascript" src="modules/mod_s5_imageslide/s5_imageslide/mootools.js"></script>');
$mainframe->addCustomHeadTag('<script language="javascript" type="text/javascript" src="modules/mod_s5_imageslide/s5_imageslide/class.noobSlide.packed.js"></script>');
replace it with:
echo '<script language="javascript" type="text/javascript" src="modules/mod_s5_imageslide/s5_imageslide/mootools.js"></script>';
echo'<script language="javascript" type="text/javascript" src="modules/mod_s5_imageslide/s5_imageslide/class.noobSlide.packed.js"></script>';