Attach Screenshot Applet - unable to use with Firefox 4

Firefox 4.0 (Mac OS X 10.6.7)

If I select More Actions/Attach Screenshot – I get sent to a page telling me to use Software Update to ensure I've got the latest version of Java installed.

I was just able to get this error by attempting to load the attach screenshot applet on jira.atlassian.com as well as on the installation of Jira where I work.

$ java -version
java version "1.6.0_24"
Java(TM) SE Runtime Environment (build 1.6.0_24-b07-334-10M3326)
Java HotSpot(TM) 64-Bit Server VM (build 19.1-b02-334, mixed mode)

The following page does report that my java is working (in Firefox 4)
http://www.java.com/en/download/testjava.jsp
Java SE 6 Update 24