ssl and popups

Hi all

I've got a section on a website the is using ssl(https). any link that I Use on that page works fine and the secure pages continue fine. The problem is that on the first page there is a gif that bring's up a popup displaying help of that screen, but when you click on it say's that a security problem has occured. check it out for yourself

goto http://www.mortgagelinked.co.uk/partners.asp?id=ndl and click on apply-online

Any ideas greatly appreciated

ian