I have an application that uses Actionscript 1 that was written under Flash mx. It connects to the server via XMLSocket, and worked great until Flash 9. I can see the application request the policy document from the policy server. It connects through the socket but does not transmit data or throw an error. It just sits there.
If I execute a reload after a few seconds with loadMovieNum(_url, 0), it works fine. I suspect I may be dealing with a timing problem. I would appreciate any insight that would help avoid rewriting in Actionscript 3.
flash players have been implementing more and more security features with each version since 8. you almost certainly have encountered a cross-domain security issue that's been implement in flash 9 and was not present in previous player versions.
here's a link to some info and a link to the flash 9 security white paper: http://www.adobe.com/devnet/flashplayer/articles/cross_domain_policy.html
but fp 10 is even more restictive so you may want to read about the general flash roadmap for fp security.