Therefore it won't work until this issue gets resolved.
Thanks, at least I'm not alone. According to Xeno86, it should work for him:
It must be something wrong with your configuration, because I use Firefox 3.0.7 with Flash 10 everyday and it works for everybody else.
My suggestion is to do clear install of Firefox 3 and creating a new profile.
I tried using new profile but still failing. I'm uncertain whether Firefox 3 is mandatory though.