Java or JavaScript?

My computer just made the upgrade from Firefox 3.x to 4.01. We are using a webpage where the Java run-time environment is a must. Previously it was OK. With the new version the web page it telling me to install the Java environment. I made the reinstall but still not OK. With IE8 or Chrome it is OK but the Firefox failed. What shell I do?

Instead of a replay I got a similar question like my one.And an other question vether it was helpful or not.What a scandal it is? Why such a wrong browser for me?And why such a weak support?I spent half an hour for register and no success! (My question was:How to enable Jawa on my new Firefox 4) I'll try to have other browser to my Ubuntu.