Although you re-activated the hiding of page source code, i found the possible cause of the problem.
When in Chrome there are different javascript files loaded than when in firefox:
Chrome:
<script type="text/javascript" src="http://www.guttpassion.ch-chrome_files/jquery.js"></script>
<script type="text/javascript" src="http://www.guttpassion.ch-chrome_files/roundies.js"></script>
<script type="text/javascript" src="http://www.guttpassion.ch-chrome_files/jquery-ui-1.7.2.custom.min.js"></script>
<script type="text/javascript" src="http://www.guttpassion.ch-chrome_files/jquery.mycolorpicker.js"></script>
<script type="text/javascript" src="http://www.guttpassion.ch-chrome_files/wppa.min.js"></script>
Firefox:
<script type='text/javascript' src='http://www.guttpassion.ch/wp-includes/js/jquery/jquery.js?ver=1.8.3'></script>
<script type='text/javascript' src='http://www.guttpassion.ch/wp-content/plugins/cispm-contact-mail/js/roundies.js?ver=3.5.1'></script>
<script type='text/javascript' src='http://www.guttpassion.ch/wp-content/plugins/cispm-contact-mail/js/jquery-ui-1.7.2.custom.min.js?ver=3.5.1'></script>
<script type='text/javascript' src='http://www.guttpassion.ch/wp-content/plugins/cispm-contact-mail/js/jquery.mycolorpicker.js?ver=3.5.1'></script>
<script type='text/javascript' src='http://www.guttpassion.ch/wp-content/plugins/wp-photo-album-plus/wppa.min.js?ver=3.5.1'></script>
As i explained before i can not investigate further as you do not give me sufficient access.
Look in you theme or other plugins why e.g. in chrome the standard wp jquery files are not loaded.
When i take a saved source from the firefox browser and run it in chrome, the slideshow starts as expected. So i am sure the problem is not in wppa+ but in your theme or an other plugin.
Case closed.
Yeah sorry I reactivated my plugins protection because I thought you had finish with it.
But anyway, it’s working now with the start/stop bar so I’m ok with that.
Thanks a lot for your help