You only need the most current one that you have 6.0.18. Try to un-install the other 3 using Tools > Add-ons > Extensions, -click on Java Console 6.0.11, click Uninstall -click on Java Console 6.0.13, click Uninstall -click on Java Console 6.0.15, click Uninstall When all 3 are done, click Restart Firefox in the Extensions window. When Firefox has restarted, go to Tools > Add-ons > Extensions and see if only Java Console 6.0.18 remains. Hopefully this will remove the 3 old versions; the manual method is a little more complex. If not post back here before continuing with the update below.

Also check your versions of Shockwave Flash (aka Adobe FlashPlayer) and Shockwave for Director (aka Shockwave Player) at this link: http://www.mozilla.com/en-US/plugincheck/ Someone can give you the links and instructions for updating these 2 items if they are out-of-date.

Other Issues: ~~red:You have installed plug-ins with known security issues. You should update them immediately.~~

Update Java: your ver. 1.6.0.18; current ver. 1.6.0.20 (important security update 04-15-2010) (Firefox 3.6 and above requires Java 1.6.0.10 and above; see: http://support.mozilla.com/en-US/kb/Java-related+issues#Java_does_not_work_in_Firefox_3_6 ) (Windows users: Do the manual update; very easy.) See: Updating Java Do the update with Firefox closed.

See: http://kb.mozillazine.org/Java#Multiple_Java_Console_extensions http://forums.mozillazine.org/viewtopic.php?f=38&t=1708795 - Java Console extensions http://forums.mozillazine.org/viewtopic.php?f=38&t=1710075 - Upgrade to FF 3.6 added many Java Console addons

Thank you both but no, the manual method does not work. 'Uninstall' is greyed out. Do I have to go to a specific folder in order to remove them?

Yes. The folders are located in Program Files\Mozilla Firefox\extensions. In your case, you should be looking for the following to delete. You can move or rename them, if you prefer, to be sure you have the correct folders; once verified you can then delete the folders that were moved or renamed (see: http://kb.mozillazine.org/Java#Multiple_Java_Console_extensions ):

 (highlight added)
 (highlight added)
 (highlight added)

Restart Firefox. That will leave only Java Console 6.0.18 in Tools > Add-ons > Extensions.

Then do the Java update so that you have version 6.0.20.

You can remove the deleted items from your Recycle Bin when you are satisfied that the changes have been made.

Have you checked your versions of Shockwave Flash and Director for Shockwave as outlined above?

How can I get rid of the Java plugins leftovers? I installed Java 1.6 update 20, and now I have two entries:

Java 6 U13 Java 6 U20

This is annoying and Sun should fix that shit for their upcoming updates.

Deleting the folder worked. It was the only thing in "C:\Program Files (x86)\Mozilla Firefox\extensions". Other extensions are stored in a different user folder, so it shouldn't be hard to find. You can go into the extension's folder and view install.rdf in a text editor and look for the words "Java Console" to confirm.

Thankfully Firefox 8 prevents this crap from being installed automatically, so it shouldn't be a problem anymore.