Windows Defender Error Application failed to intialize: 0x800700c1.

Question

The other night my laptop downloaded a definition file via Windows Auto-Update (which stupidly I never deactivated). This update failed according to the Update History. Now Windows Defender will not run. When Vista first logs on I get the message listed in the subject of this thread. I also get the same error message when I try to open Windows Defender from the Start menu. I contacted a Dell support guy, and we tried many, many things to fix this, including system restores, CMD inputs, removal of all definitions, and a bunch of other stuff. Much to both of our dismay nothing seemed to work. I really applaud Dell for giving support for a product they didn't create. Microsoft really put you Dell guys in a bad spot with Vista's lack of usability, and their lack of support for their own IP. If anyone has a clue about this PLEASE help me. I HATE seeing error messages every time I turn on my computer. Below are my system specs: Windows Vista Home Premium 32 bit Intel Core 2 Duo T5250 @ 1.50GHz 2.0 GB RAM NIVIDIA GeForce 8400m GS Creative Sound Blaster Xtreme Audio Notebook (ExpressCard)

mombodog · Answer

Manually download and install the latest Defender definitions from here.   http://www.microsoft.com/security/portal/ADL.aspx

C3PO5 · Answer

I really applaud Dell for giving support for a product they didn't create. Yes But when Dell bought the rights to use XP and Vista OEM software Dell also bought the support for it and then Dell supports it for 30 days to you after that its your baby ! Microsoft supports the { {Retail version}} not any OEM version be it Dell Compaq Gateway HP and any OEM version you buy off of the internet or from a computer shop!!    Check the antivirus you are running it may have it own defender i know McAfee turns windows defender off and uses its own protection process! And it will not let windows use the defender updates it needs . Good Luck

C3PO5 · Answer

I completely disabled McAfee, Hi I do not know what to tell you other than when McAfee was on my 2 new computers i did not like how it worked with windows by trying to control every thing on it ,  so i do not use it at all it gave me to many problems with the windows updates so off it went ! And i got one that did not have all of the problems that McAfee seems to have!!   Good Luck

Aquayogi · Answer

I completely disabled McAfee, and retried the update to no avail.

Aquayogi · Answer

tried this, and no go...

tgsmith · Answer

Aquayogi,   I know this is going to sound stupid, but have you double-checked your date setting?  Had this happen once when an XP system was set one month ahead.  Windows update saw the system date as January 1, 2007 when it was actually December 1, 2006.   Tony

Aquayogi · Answer

No, my date is accurate.

Windows General

Windows Defender Error Application failed to intialize: 0x800700c1.

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