When my web pages load, there's a flash of white before the page actually loads. The pages have a 955x100 flash animation on them. Remove the flash animation, the problem goes away. All solutions I read said "wmode - transparent" or occasionally the mention the FOUS problem/solution. Neither did anything.
I finally figured out what's wrong. When I add a .swf to my web page, the browser (IE, Firefox, Safari) loads the .swf first and then the css background image. This is what is causing the flicker. It's easily testable:
1. Make a new Flash file.
2. Publish the Flash file.
3. Add a background image to the .html page.
When you test the page, even with an empty .swf and a 20k background image, there .swf loads first and then after a slight delay the background image loads.