Css gets messed up very very often

Hi, I'm curious how to solve this problem. This week, almost daily I have to empty all caches in W3 total cache to get the lay out as it should be. Nothing changed on the website, but it does get annoying that a potential customer gets a messed up page. I thought I could add a screenshot?? Well, lets decribe it then. Instead of the proper menu I get only all links from the menu below my site logo. This is not in the form of a menu, but in the form of a list For now it's fixed, but please have a look, this is a very major problem. (url of the problematic page in link)