An anonymous reader writes "While doing a weekly scrub of my Windows systems, which includes checking for driver updates and running virus scans, I found Firefox notifying me of a new add-on. It's labelled 'Microsoft .NET Framework Assistant,' and it 'Adds ClickOnce support and the ability to report installed .NET versions to the web server.' The add-on could not be uninstalled in the usual way. A little Net searching turned up a number of sites offering advice on getting rid of the unrequested add-on."
The unasked-for extension has been hitchhiking along with updates to Visual Studio, and perhaps other products that depend on .NET, since August. It appears to have gone wider recently, coming in with updates to XP SP3.