Using Internet Explorer?
Go to 'Tools'
at the top of your browser window and select 'Internet Options'.
Click on the 'Privacy' tab, and move the slider down a notch. (I have to set mine to 'low' with Internet Explorer 7.)
Click 'Apply' at the bottom, then 'Ok'.
Now try again! If it doesn't work, send us an email :)
(And remember to set your Privacy tab slider back up again afterwards if you want to!)