can no longer update Defender

[Guest]

1.0.0.0 Yesterday I started getting into a loop where I was notified there
was a new definition update, which I would download and then install, but 10
seconds later I was prompted again about the same update - and looking in
Defender itself it still showed the previous signature version. In the end I
uninstalled and reinstalled. The signature that shows as installed is now
from January 2006, but whenever I try to update I'm told I am already
uptodate, but it's obvious that I'm way out of date.

Any ideas?

 

[Bill Sanderson MVP]

What happens if you do the resolution steps in this article:

http://support.microsoft.com/?kbid=915105