I was just attempting to patch a Windows Server 2008 R2 VM when Windows Update failed with error 0x80243004, which wasn’t familiar. A little Googling revealed the source of the problem, and the improbable fix:
Windows Update was failing because it couldn’t display the icon in the systray! The systray was misbehaving, with lots of empty space but no icons showing.
The solution is to resize the systray, show all systray icons, or just set the Windows Update icon to always “Show icon and notifications”.
The last post in this this Microsoft forum thread discussing this bug makes me chuckle too: even Microsoft couldn’t fix it, but at least they went ahead and posted the work-around.