Amazon affiliate link shows pop-up Advertising

Hi Jochen
This is not standard WordPress functionality so it is most likely coming from a plugin or theme. I would recommend looking through your installed plugins and disabling any that mention Amazon specifcally.

If you cannot see anything obvious there is a possibility your site has been hacked (made more likely by the fact the site is still on version 3.5). There is a great article on the codex about what to do if this is the case: http://codex.wordpress.org/FAQ_My_site_was_hacked

My recommendation would be to download a copy of your website on to your local machine and then search the code for “wwwdampfreini-21”. That should give you an indication as to what is adding the script (plugin, theme or something more sinister).