Umm, if I remember correctly, the reason some flash sites work fine and others don't, is because some of the flash sitesa use shockwave. And unless you have that plugin installed, you're going to have problems.
I've been having the same problem and have been actively searching the internet for a way to get the plugin to work in Linux. While flash player 7 is available for Linux based systems, shockwave is not.
If anyone has found out anything else, it would be greatly appreciated.