How did we miss this one? It seems some HTC Titans who shipped with bootloader 2.2.160015.3(134181) have been completely unable to update via the Zune Desktop client, generating Error Code: 80070013 / 8007000F.
Fortunately the news of the flaw comes at the same time as the news of a fix, with HTC releasing a SPL which can be flashed to the device from the desktop and which will then allow normal updates. The update will only overwrite the bootloader and not affect the data on the device.
Our tipster reports after flashing the update he was finally able to install the 8107 update successfully, after months of waiting.
The SLP can be found at HTC here.
Thanks Phil for the tip.