How do I… open windows explorer at a pre-set location

Create a shortcut to Windows explorer (probably on your desktop)
Add /e,C:\Windows to the end of the shortcut

http://support.microsoft.com/kb/307856

Windows Explorer remove add-in context menu

 

Export suspect registry key from. Then delete test. If not better then import saved.

HKEY_CLASSES_ROOT\Folder\shellex\ContextMenuHandlers