Windows 8 on Desktop 8: Failure configuring Windows updates

I just (today) bought Parallels Desktop 8 (switched from VMWare Fusion with Windows 7) for my Macbook Air, summer 2011, running Mountain Lion with all updates, and did a clean install of Windows 8. All went fine. Then I installed the Windows updates. The first four of them went fine.

Then came "Update for Windows 8 for x64-based systems (KB2756872)". This installed, rebooted, and at 98% configuration ended with "Failure configuring Windows updates, reverting changes, ...".

I ran the Windows Update Troubleshooter from http://support.microsoft.com/kb/949358#method1, tried a second install of the update, with the same result (Failure configuring ... at 98%).

I also did a clean install of my Windows PC with Windows 8, and installed all 13 updates successfully. What could be wrong with my Parallels installation?