Can't log in to Members Research Panel

Hi,

I have a problem if I want to log into the members research panel on the web site.  It asks for a user name and password.  I am already logged in to teh CC web site when I click on the MRP link.

 I only get this problem on my home PC.  Everything works as I would expect on my wife's laptop, work PC, or even my smart phone.

I put it down to something on my desktop PC, but last weekend I did a complete rebuild of my hard disk, with a clean, fresh install of a  new operating sytem which is windows 8.  But I still get the same message.

Can anyone help?