It is the same problem as everybody else, nothing different. Your hosting company simply changed something in their server adress (what we call "absolute path"). The plugin is using that "adress". That is why, now it can't reach one file, and is showing a warning message.
The warning message is giving you the right "path" : /home/yngvilvg/public_html/wp-content/advanced-cache.php
You will need to correct that "path" by hand. I suggest you find someone able to do it for you, or simply disable the plugin (if you are able to reach it). It is a really simple job, but if you know nothing about those things, it can be hard to understand. Also, your username and password are needed to reach that file (by the server control panel or by FTP).