Windows Security Center - Windows Defender Out of Date

[Boolean1]

Why does my Windows Defender show as Out of Date?

When I click Update Now, Security Center goes out updates definitions for
Windows Defender, but...then I get the message: "there are no new
definitions to download for Windows Defender.

What's going on with this?

Thanks,

Boolean1

 

[dean-dean]

Try this. Go to http://www.microsoft.com/security/portal/

Under "Latest Definition Updates", choose your operating system type, 32-bit
or 64-bit, and try the manual download. Note here the instructions
pertinent to Vista: http://www.microsoft.com/security/portal/ADL.aspx#top

After this, is it shown as being out of date?