Page Caching is not working for me. When I have this option enabled everytime I open uncached page my browser shows me the message: "Error 503 Service Unavailable". When I hit F5 after that message, page loads fine. This 503 Error comes from Varnish but with Varnish disabled I have excatly the same problem (insted of 503 error message I get a blank page).
BTW. I don't know why but when I enable Page Cache debug mode everything works fine.