Mozzila firefox and applets problem

[Biggie_mac]

I have the latest version of mozzila firefox 1.5.0.1. I am working on some projects at my school involving servlets and I had to instal the latest version of java on the computer. But first I deleted the old one. Now the browser doesn't open applets. it shows "install missing plugin" and when I click on the button it says that I'm missing Java runtime edition...I click install and after a couple of minutes in which it tries to do something it says "u already have the latest java installed on your computer. First uninstall that version before installing it again" or something like that. I don't want to uninstall it beacuse the kit is big(130mb) and I already have it on my computer. If I uninstal and let mozzila install it then he will download the kit again and that takes a lot of time. Does anybody know if there is another solution?

I cleared the cache of the computer, I uninstalled and reinstalled mozzila. nothing so far....