Seems that Microsoft is considering now adding extensions to Firefox in order not to loose market share in the browser (a war is restarting?)
I've notice on Sunday evening the install of a new (HIDDEN) Firefox add-on
XP don’t display this add-on so it CANT be removed easily using the add-on manager
VISTA display the add-on “Microsoft .Net Framework Assistant” but uninstalling it in Firefox, restarting do not WORK
Attention: you will encounter this issue
if you run Microsoft Update and install Microsoft .NET 3.5
If you install Microsoft Visual Studio 2008 (which require the above component)
Removing it wont make you loose a lot of things:
"Adds ClickOnce support and the ability to report installed .NET versions to the web server”
How to remove it
You'll have to hack the registry of Windows for now :-(
Open your Start Menu and choose Run.
Type in regedit and click OK.
Within there, you have to look for something like calledHKEY_LOCAL_MACHINE\SOFTWARE\Mozilla\Firefox\extensions and delete the key there For Windows Vista 64-bit HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Mozilla\Firefox\Extensions
Type in Firefox about:config in the address bar in Firefox, accept the warning
Open Windows Explorer and go to\WINDOWS\Microsoft.NET\Framework\v3.5\Windows Presentation Foundation\DotNetAssistantExtension\ to remove the last remnants of the evil extension.