SSL problems with Dashboard after clicking on "add a new gadget"

I am using MSIE 8.0.7600.16385 with https://support.atlassian.com/secure/Dashboard.jspa. After logging in, I see the default empty dashboard. When I click on "add a new gadget", MSIE displays a warning "do you want to display only those items that have been transmitted over a secure channel". Firefox does not show a warning.

This warning is ususally shown when some objects (images, stylesheets?) do not have the same URL (https://support.atlassian.com in this case) as the rest of the page.