Flash movie not loading when browsing secure site

I installed the secure certificate, browsed the website with all the browsers I have, everything worked fine. But guess what, I missed one small section of the website when testing it with IE. Since I don’t use it, I never noticed anything. I got a call from the customer saying that it was not working, but only when using IE. What? Flash not working with IE? I am used to CSS not working in IE, but Flash?

Making a long story short, the fact was that the movie wouldn’t load under https, but would load fine under http. I finally found that all the files under that directory were not getting cached thanks to the content expiration setting in IIS, and that, combined with SSL, made IE not able to load the Flash movie.

Changing the content expiration setting from “immediately” to a small period of time solved the problem.