I have my WordPress on the root of website and I have actived W3TC but its htacces' rules of cache are affecting the behaviour of my forum at /forum directory. In particular when a page of the forum is changed, the browsers show the old page and to see changes you must force a page reload or you must disable browser cache. In this way when you login, then the page shows that you are not logged in, or when you post a message, you can't see the message posted.
By now I have added a "no-cache header" to my forum's pages, but this is not acceptable.
How can I exclude the /forum directory at all?