Three possibilities of which I am aware:
1. Internet Explorer \ Tools Menu \ Internet Options \ Advanced Tab. Scroll
down to the entry for Java (Sun) and make sure the checkbox for "Use Java 2
v#.#.#_## for <applet>" is checked. You will have to OK the Internet
Options dialog and restart your computer for this to take effect.
2. Internet Explorer \ Tools Menu \ Internet Options \ Security. Click on
the Internet entry, then click the Custom Level button. Scroll down to
Microsoft VM \ Java Permissions and make sure it is not set to Disable Java.
Then scroll down to Scripting \ Active Scripting and \ Scripting of Java
Applets and make sure they are both set to Enable.
3. Control Panel \ Java Plug-In. Make sure the Enable Java Plug-In checkbox
on the Basic Tab is checked, and do the same for the Microsoft Internet
Explorer checkbox on the Browser Tab
Hope those help!
- Mike