Error 0×80040002 is a standard COM error that related to E_NOINTERFACE,
which means some COM DLL components on the system is not correctly
registered, or has become corrupted.
To solve and fix the 80040002 stop error on Windows Vista Update, try the
following resolution to re-register the Windows Update related DLLs.
Open an elevated command prompt, and type the following commands. Press
'ENTER' key after each command:
regsvr32 wuapi.dll
regsvr32 wuaueng.dll
regsvr32 wuaueng1.dll
regsvr32 wucltui.dll
regsvr32 wups.dll
regsvr32 wups2.dll
regsvr32 wuweb.dll
There may be some errors on registering of the DLL, which can be ignored.
Once re-registered, check for updates again. In most case, Automatic Update
will work almost immediately. If this trick does not work, try to disable
UAC. You can always re-enable the UAC once the Windows Update gets working
again.