I have been using W3 Total Cache for years now, and this is the first time i ever saw this problem.
Today while i was taking a look at my logs i saw a 404 error in front page, so i went to the browser to take a look and surprise... front page was really giving me 404.
I desactivated all plugins and activated one by one... and when i activate W3 Total Cache, booom... 404 error. Then i desactivated everything again, deleted W3 Total Cache and downloaded the dev version (10 months old?). Activated only the dev version... and got 404 page, so yeah... W3 Total Cache is the issue here.
I have a VPS with 768MB RAM and 1 core CPU. I use Nginx as my webserver and php-fpm for PHP. I also use Varnish, APC and CloudFlare Pro if that counts.
I have been in this VPS that i setup for about 15 days, and this is the first time i saw this error. It actualy showed up on the acess log only today, so i really have no clue about why it happened... it also happens only in front page, any other pages are works fine and posts too.
This my default.conf Nginx's config: http://paste.ubuntu.com/1063432/
My Nginx's main config looks like this: http://paste.ubuntu.com/1063434/
My php-fpm default pool looks like this: http://paste.ubuntu.com/1063435/
The only change i did on my website today was change php-fpm settings from dynamic to ondemand, but i changed it back and error still happens.
Right now i have disabled W3 Total Cache and setup CloudFlare to do the minify, configured browser cache direcly in Nginx and let WP's default cache active (same for php's one)... but website is slower ofc, since i don't have all the great stuffs of W3 Total Cache on.
So... anyone can help me with this or have experienced the same problem? I really love this plugin, but Frederick don't really help and all he does in the rare ocasions he appears is say "it's fixed in the next release"... i understand he is a busy man with Mashable being a huge site and all, but... damm :/