I am running Windows 8.1 Pro with Media Center. It is a 64-bit edition.
I downloaded the Windows 8.1 Update from MSDN. Installed it on two machines with no problems.
Update is a series of 6 updates packed in a single zip file. Unzipped the files. Went to install the first recommended update (KB2919442). Dialog box indicated it was already installed.
Went to install the second update (KB2919355). It ran through the dialogs and said installation completed. It indicated that a reboot was necessary. Rebooted. It began to install the update after the reboot. Got about 60% of the way through, then said it couldn't complete. Error message 800F0092.
Had successfully installed on two other machines, one a VM and one a Samsung tablet. Only difference is this computer is 1) Media Center, and 2) was running WebRoot antimalware agent.
Retried the install. Got about 98% through the dialog (green progress bar almost at 100%), went it stopped and the dialog said Update Failed.
Error message in the update history is now 80073712.