In an effort to improve your user experience we are currently implementing a system to make our site faster, however this is currently causing some login issues for some of our customers
This is simply due to a cookie gone stale :-( We are currently working to fix this, in the meantime...
A quick way to clear your cookies is to simply hold Ctrl + Shift + Delete then select "clear browsing data" (firefox) or "clear now" (Chrome) or "Delete" (IE)
this will clear all your cookies. Using a different browser should also bear fruit (or fresh cookies)