I am really sorry for the delay of this reply as it is a weekend for us here. Is it possible for you to provide us with the back end and FTP access to your site to check on this issue?
I'm really sorry that delayed of this reply,
I have tried to disable your "Search Engine Friendly URLs" and "Use URL rewriting" from your backend global configuration, everything is work fine, may i know do you have install some 3rd party component or plugin to rewrite the URL in your site?
If yes, try to temporary disable it and see if that could help, If no, please refer back to us.