WebPageTest showing 403 forbidden error with W3C cloudflare

Hello,

I have configured one of my blog with W3TC + CloudFlare (NS changed, security set to high). Problem is, when I am trying to run WebPageTest now (Dalles,VA) it is showing 403 Forbidden error.

Response header is :

HTTP/1.1 403 Forbidden
Server: cloudflare-nginx
Date: Sat, 13 Aug 2011 14:59:05 GMT
Content-Type: text/html

It was absolutely right from the same location few hours ago : http://www.webpagetest.org/result/110813_1F_1ADGQ/1/details/

There is no problem if the test is run from other location like Atlanta, GA or NYC.

What to do?