Unable to access the Store with Forefront TMG Client webbrowser enabled error 0x80072efd

Hi,

I have a problem when users are trying to access the store when this option 'Enable Web Browser automatic configuration' is enabled from the Web Browser tab in Forefront TMG Client Version 7 on Windows 8.1 x64.

If this option is un-ticked and the proxy details are set in IE users can access the store ok.

The error message users receive is:

We weren't able to connect to the store. this might have happened because of a server problem or net then work connection timed out. please wait a few minutes and try again.
0x80072efd

When the option is selected in Forefront TMG everything else works ok, the user can access the internet etc its just the store which doesnt work.