Windows Defender fails to initialize - error 0x800106ba

I just started getting this error (under Vista Home Premium SP1, up to
date).

I Googled and tried a few things such as 'net start windefend' at an
elevated command prompt. (That command also works fine at Run.) That opens
the program and it runs just fine, but when I reboot, I receive that same
message - something like - Windows Defender failed to initialze 0x800106ba.
I am told to reboot and check Help or something like that.

I tried to remove it under Control Panel \ Programs and Features but it's
not listed. If I could have uninstalled it, I would have tried a fresh
install but that seems not to be possible.

Ideas? Suggestions? (I also looked for a Defender forum in
news.microsoft.com, but there isn't one. I thought it OK to post here.)

Thanks, Dave Horne

More info - If I uninstall McAfee Security Center 9.3, this problem goes
away. Since the items protected by Defender are already covered by McAfee,
is there a way to either uninstall it or turn it permanently off?

Rollback, do a restore point back to a point before the problem started
happening, that's if you have restore points active.

Or you might try this.

http://support.microsoft.com/kb/929833

You will not be able to use windows defender when you have mcafee
installed. like other anti-virus softwares, mcafee will disable windows
firewall and defender to avoid duplicate notifications.

uninstalling and reinstalling mcafee would fix this issue (it would
reconfigure). but in your case you can uncheck windows defender from
startup items (msconfig) 'Article'
(http://support.microsoft.com/kb/929135) and set windows defender
service to Manual and stop the service.

Dave,

Have you fixed it yet? I am having exactly the same problem. I can not find
Windows Defender in control panel to delet as suggested on microsoft.com.

Nothing seems to be helping but apparently there is free download called
Regcure, but i'm not too sure about downaloading when I have security issues!

Pls help if you can !

Hello Marcia,

I had the same problem with "application fail 0x800106ba" message. The
problem started after I renew my subscription for McAfee Security centre.
What I did was I followed the steps of the article:
www.support.microsft.com/kb/929135 When I went to step 2 I just unchecked
McAfee site advisor box since this was the only difference with the previous
version of the Security centre I used. After I restarted the computer the
problem disapeared. I put back all previous setting and everything seems
fine. I didn't want to use the site advisor option of McAfee but even after I
unchecked it, it still works.
Some guys suggested unticking the Defender box but I found it too drastic...
So try the steps of the article..play with the boxes and I hope is going to
work for you as well.
Regatds.

The 2009 McAfee consumer products for Windows Vista disable Microsoft Windows
Defender to improve system performance.If that 'error' message appears,
ignore it, or enable Windows Defender (Start \ Run \ services.msc) and then
turn off automatic scanning (in Windows Defender).