As Mozilla released a new version of the popular open source browser, Firefox 3.6 many add-ons will stop working. Previous workarounds to enable extensions may not work. However there are two new workarounds that will make your favorite plugins work with the new version of Firefox.
The first one is an extension called Add-on Compatibility Reporter After installing the Add-on Compatibility Reporter, your incompatible extensions will become enabled for you to test whether they still work with the version of Firefox or Thunderbird that you’re using. If you notice that one of your add-ons doesn’t seem to be working the same way it did in previous versions of the application, just open the Add-ons Manager and click Compatibility next to that add-on to send a report to Mozilla.
Another method is to simply add a new configuration to Firefox. Here is how its done:
In the address bar type: about:config
Right click on the setting page and select: New->Boolean
Type: extensions.checkCompatibility.3.6 and set the value to false