I had a similar problem this week.  When I looked at the update log
there was a microsoft xml core services update that had failed
repeatedly.  I resolved the issue by canceling the update, downloading
the file directly and installing it by hand.  Since then I've had two
updates run without a hitch.

-Lyman

Ernie Buford wrote:
> Anyone else having recent issues with Windows Update?  I'm
> experiencing some issues this week and currently have 2 typically
> curious update sessions underway.
>
> One workstation, recently upgraded to Windows 7 (clean install) is
> sitting there "checking for updates".  I opened Windows Update and hit
> the "check for updates" button about an hour ago, and still the green
> "progress" bar is in motion (at least the green bar is doing
> something!).  This happened a day or 2 ago and eventually came to a
> resolution after a similarly ridiculous amount of time.
>
> Meanwhile, over on my Macbook Pro, which has also recently had a
> Windows 7 upgrade (along with Bootcamp driver upgrades for W7), I have
> the blue screen that says "installing updates; don't turn off or
> unplug your computer".  Well, the computer wasn't plugged in when I
> shutdown, so it shouldn't be trying to install updates in this state
> anyway.  I plugged in the power, and it's been at it for more than 30
> minutes.  Same thing happened at home last week.  I was watching TV in
> the evening at the time, so I just let it go, and it finally powered
> off after an hour or more.
>
> The Windows 7 honeymoon is winding down.
>
> Ernie