Microsoft's servers do tend to get swamped or Microsoft pulls a patch, reissues without notice. I give updates a week before I start investigating.
Bob
It appears that it may be Windows Defender, as that is the icon in the taskbar, although no mention whatsoever of Windows Defender is anywhere in the window itself. This has been 'updating' for five hours, with no progress at all in the, ya know, the status bar thingie.
Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic