Haven't tried it, but I know CS3/CS4 introduced some newer flash-version autodetecting JavaScript when you use the default "flash media" HTML templates, so as odd as it sounds, try loading up your non-functional flash page with JavaScript turned off and see if the Flash loads properly. There is one other way to do Flash version detecting that I'm aware of, but it's ugly and a pain, so my bet is that all the sites you're running into are probably using JavaScript detection. If that solves the problem then maybe future browsers (Tear, etc) can have some option for user JavaScript over-rides so that whenever the detection function gets called we can just have a "return true" that over-rides it. Of course if the Flash actually uses some new features of the version 10 player then you're going to end up with all kinds of bad things happening, but...