With OrderCup loaded on your FireFox browser, go to Tools --> Add-ons and then click on "Plugins" on the Left sidebar.
Scroll down until you see the section for Java Platform (see screenshot below), and change the dropdown from "Never Activate" to "Always Activate"
ADDITIONAL INFO AND OLDER FIREFOX VERSIONS
- As a general rule, never use the very latest version of FireFox unless it has been publicly released for over a month. This allows the Java and FireFox developers the time needed to make sure they work well with each other. As of 01/23/13, the FireFox version that is stable is FireFox 18.0.1 (Note: If you somehow have a newer version than 18.0.1, un-install it first!) If you have 18.0.1, go to the next step. Download it here: www.firefox.com
- Open FireFox and prevent it from automatically installing updates, by going to Tools --> Options --> Advanced, and in the Update tab, select "Check for Updates, but let me choose whether to install them". Also uncheck the box, "Use a background service to install updates" Click the "Ok" button.
- From the Windows Control Panel, open Java. Click the "General" tab, and click "Settings". Click "Delete files", and in the popup window, check all the 3 boxes and click 'Ok'. Click 'Ok' again.
- In Windows, via Control Panel, uninstall all Java Programs using the standard method for uninstalling software.
- Install the latest Java version (currently Java 7 update 13) from here: www.java.com
- From the Windows Control Panel, open Java. In the "Update" tab, un-check the box for "Check for updates automatically" (if a popup comes up, click "Do not check"). Click 'Apply'. Then in the 'Advanced' tab, under Java Plug-in, check the box for "Mozilla family" and also check the box for "Enable the next-generation Java Plugin...". Again, click 'Apply'.
- If you are on Windows XP, make sure you have Microsoft's Service Pack 3 (SP3) installed. You probably do, but check anyway.
- Reboot your PC.
If you get prompted for updating to the next major version of FireFox or Java, wait a month or so before upgrading.