ASP.net menu with SSL

I have a ASP.net 2.0 menu control inside a page in a secure (https://) website. The page functions perfectly in a non-secure (http://) website. When the secure website loads there are no errors or warnings. The problem occurrs when I mouse over any of the items on the menu that contain a submenu. A warning dialogue pops up indicating that the page contains both secure and insecure content. The page functions as normal regardless if I choose yes or no to continue. Is there anyway to not display the warning? I can set the options in the browser to not prompt for this warning but that is not a solution I can give out to customers. I have looked all over the net and have not found a solution for this problem. Any help is greatly appreciated.