First of all, thanks for this great plugin !
I've got a problem : some weeks ago, visitors of my website started to complain about an error message when trying to load the homepage. This error message looks like that :
<rss xmlns:content="http://purl.org/rss/1.0/modules/content/" xmlns:wfw="http://wellformedweb.org/CommentAPI/" xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:atom="http://www.w3.org/2005/Atom" xmlns:sy="http://purl.org/rss/1.0/modules/syndication/" xmlns:slash="http://purl.org/rss/1.0/modules/slash/" version="2.0"> <channel> <title>Website Title</title> <atom:link href="http://website.com/%3Fp-30013/feed/" rel="self" type="application/rss+xml"/> <link>http://website.com</link> <description> Website description </description> <lastBuildDate>Fri, 18 Jan 2013 14:38:01 +0000</lastBuildDate> <language>en-US</language> <sy:updatePeriod>hourly</sy:updatePeriod> <sy:updateFrequency>1</sy:updateFrequency> <generator>http://wordpress.org/?v=3.5</generator> </channel> </rss> <!-- Performance optimized by W3 Total Cache. Learn more: http://www.w3-edge.com/wordpress-plugins/ Page Caching using disk: enhanced Database Caching using disk: basic Object Caching 208/228 objects using disk: basic Served from: www.website.com @ 2013-01-18 14:38:01 -->
Emptying the cache solved the issue, but it eventually happened again. And again. So I looked further into this problem, and it appears that accessing your website with that kind of URL produce a strange behavior (a bit tricky, but somehow bots load it and it makes my website go down) : http://edmondprochain.wordpress.com/%3Fp%3D30013/feed/ (load this URL with Chrome, Firefox won't do it...)
At that moment, the page is cached as "wp-content/w3tc/pgcache/index.xml". My site is still up, the homepage is still the normal page at that moment. But when the usual "wp-content/w3tc/pgcache/index.html" is deleted (I suppose W3TC garbage collector must do it), my visitors see this index.xml page instead of the usual homepage (which consists of the ugly RSS code I posted above).
I guess all of this happen because of the strange URL whose source code can't be cached into the right directory, and finally end up in the root cache directory...
Thanks for your help !