In firefox, go to tools --> options --> content (tab) --> check the boxes next to "Enable Java" and "Enable Javascript".
If you still have no luck:
tools --> options --> content (tab) --> click the "Advanced Button" next to the java and javascript check boxes --> check the following: "Move or resize existing windows", "Raies or lower windows", "Disable or replace context menus"
Tell me if that doesn't work or if you have any questions.