I have the same problem with n-ridaz.com. Its a javascript problem with firefox. I would imagine that Sad made the site only compatible with IE. So anytime I want to go to it, I have to use IE. I dont really mind it for that one site though.
I dont know why the flash and shockwave players arent working for you. Did you install them and restart your browser? If you visited the site above using firefox it should have been did what you need. It works fine for me. You can aways ask for help in the firefox forums.