If you installed the application "Hotspot Shield" it seems to reinstall this plugin from time to time. I simply uninstall it, since Forefox tells me if a plugin has been installed. I know, its annoying. Try not to uninstall but deactivate the plugin - maybe it then cannot be activated / installed again.

I had this problem as well, this extension is located in your Firefox installation path (Default path in 32Bit Windows: C:\Program Files\Mozilla Firefox\Extensions\) and NOT in your Firefox profile folder.

In order to remove it:

1. Close Firefox

2. Navigate to your extension folder in the Firefox installation path (Default in 32Bit Windows: C:\Program Files\Mozilla Firefox\Extensions\)

3. Delete the afurladvisor extension folder.

Personally I have not used Hotspot Shield software as it has crashed my computer during installation (Windows 7 Pro 32-Bit). So I could never "uninstall" it normally...

Hope this helps...

EKEagle