When I updated Drupal to 7.24, the status report instructed me to twiddle my .htaccess files per security advisory SA-CORE-2013-003, so I did. And then my site unthemed itself. A quick trip to the error log revealed the problem, and even the solution: change FollowSymLinks to SymLinksIfOwnerMatch.
Thanks, Ubuntu, for producing a tool that performs unattended updates and calling it unattended upgrades. Was hiding the fact that you don't do unattended upgrades a key feature or just a bonus?
Well, I made a nice fresh install of Windows XP with SP3 slipstreamed and got 0x8024402F running Windows Update. Long story short, the Automatic Updates service was not running. WTF? Run "services.msc" (or use computer management, etc etc) and check to see if this service is operative before running through your other options.