I get prompt have JavaScript turned off or an

Hello,
I get the prompt that I either have JavaScript (and I looked and it is not disabled) turned off or an old version of Macromedia's Flash Player, but I have the latest Firefox browser, and the latest Adobe Flashplayer 10 including the Flash Player Plug In - I get this prompt on certain sites like myspace. What can I do?

For securtiy I have McAfee Security Suite.