Flash and secure sites— ie warnings help!

I’m a mac user and I use either safari or firefox. HATE internet explorer (IE). BUT I still feel I need to design and create IE friendly sites. One thing that I’ve come across is a secure login I’ve created in flash. With everyother browser in the world I can go to the login and everything is the same as if I were going to any other secure site. BUT with IE on windows I get a warning,
“this site contains both secure and non secure items…” I then can choose to display or not to display the unsecure items. The strange thing is that NOTHING changes. I’m sure it’s my flash file .swf that’s causing the problem, BUT at the same time I came across a flash site that’s secure but no warning.
here’s the site that no warning pops up:

SO my question is it possible to avoid this warning? how’d they do it? HELP PLEASE!