How to manually remove stubborn add ons in Internet Explorer.
Set a manual restore point
Double click the add on, you will get a pop up window, hit the copy button and save to a text file, close IE, then copy the Class ID number with brackets from the text file, then search (> Keys) (match whole string only) the registry for this string, then delete all found from the registry, there may be many of these unique keys, use F3 to find all of them.
Be sure to collapse the registry before you start the search.

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collapsed


Example Text:
Name: Groove GFS Browser Helper
Publisher: Microsoft Corporation
Type: Browser Helper Object
Version: 14.0.4761.0
File date:
Date last accessed: Today, April 08, 2011, 2 minutes ago
Class ID: {72853161-30C5-4D22-B7F9-0BBC1D38A37E}
Use count: 1
Block count: 21
File: GROOVEEX.DLL
Folder: C:\Program Files (x86)\Microsoft Office\Office14