Disable mod_pagespeed (no server conf access, .htaccess doesn't work)
Create a .htaccess
file, add below text and upload using ftp program. We are also a hosting provider and use Pagespeed.
Modpagespeed Off
Your URL can accept the PageSpeed
query-paramter with an off
or on
value.
http://www.example.com/index.html?PageSpeed=off
or
http://www.example.com/index.html?q=foo&PageSpeed=off
more here.
Which hosting provider? Can you make sure your server is Apache rather than nginx? nginx doesn't support .htaccess files, though the PageSpeed module is otherwise very similar in function.
Also check out the 'pedantic' filter: https://developers.google.com/speed/pagespeed/module/filter-pedantic, which let's you get all the speed & bandwidth benefits of PageSpeed but still have a validation-clean site.