Yeah, the same thing happened to me. I installed my windows vista home
premium but wasn't directed and forgot to uninstall windows defender beta 2
before the install. After a couple of days i realized that defender wasn't
working correctly and uninstalled the beta version but was unable to enable
the vista version. This is very frustrating as i was looking forward to
using windows defender. I have been in contact with a help and support tech
and tried various things. However none of them worked and in the end all she
could offer was for me to switch to a 3rd party anti spyware or do a complete
reinstall which would wipe everything.
Very dissapointed, please help with any ideas

"PCoutlet" wrote:

> We have another thread going where several of us are having the same sort of
> problem. I get the same error: Application Failed to initialize: 0x80070002
> I am also running Windows Live OneCare.
>
> "jameshazy" wrote:
>
> > After I upgraded to Vista Ultimate from XP SP2 - I recieve a startup error
> > that Windows Defender can't be started. Try again later - or application
> > failed to initialize: 0x80070002.
> >
> > Any ideas? The system will not let me uninstall or reinstall the
> > downloadable, as it is indicated tht Windows Defender is already installed
> > with Vista. Seems I am stuck. Windows Update will not successfully update
> > Defender so...