Right now you can see it hanging up on "supports concrete5 request URLs" and "cookies enabled":http://c5.sitetestingserver.com/...
It doesn't provide an error, it just hangs there.
I've had no issues with past installations. Any thoughts?
I would contact your host and ask them about it.
You can also try this for kicks and giggles....
In regards to the Support Concrete5 request URL's error....create a file called php5.ini using text editor. Paste this line cgi.fix_pathinfo = 1
and save the php5.ini file. Once that is done, upload it to the root of your website.
Hope this helps.
<IfModule mod_security.c> SecFilterEngine Off SecFilterScanPOST Off </IfModule>
From there, the installation process works fine.