Linux + iPlayer in school

I am in school and trying to use BBC iPlayer from my linux laptop but get an error when the streaming starts. It works fine at home and the XP machines in school work fine as well so I am scratching my head.

The error is "A script in this movie is causing Adobe Flash Player 10 to run slowly. If it continues to run, your computer may become unresponsive. Do you want to abort the script? "

Using Fedora 11 but was the same under Ubuntu 9.04 and 8.10.
Firefox 3.5 beta and Flash 64bit.

Any ideas gratefully received :)