Conditional Statement in mailing causes parse error
I fixed this by adding (as @Andrei suggested) config.entities = false; to my config.js file in the ckeditor (/your/path/to/civicrm/civicrm/packages/ckeditor/config.js).

Just don't forget: If you are modifying config.js you should first have configured a Custom PHP Path under Administer > System Settings > Directories, and place your modified version in the custom path.