I was investigating a problem with Windows Updates on a laptop with a lot of software on it from a previous user. The updates having problems were the Windows 7 Monthly Cumulative Security patches.
Windows Update would download the patch, install the patch, and then ask to reboot Windows to complete the install. Once the PC rebooted, the screen would show that Windows was installing updates and sit there at 32%. The system would eventually reboot itself and change the status to "Failure Configuring Windows Updates. Reverting Changes. Do Not Turn Off Your Computer." This whole process would take anywhere between 60 - 90 minutes before changes were reverted and I could get back into the system.
Through a remote console, I connected to the system and wrote down what I observed, including the time. What I saw were 3 reboots 15 minutes apart with the screen sitting at 32%. The 15 minutes apart seemed to be consistent. It was also observed that the Trusted Installer process had high CPU utilization.
From this information, I searched more specifically at CBS log error "Startup: A possible hang was detected on the last boot. [HRESULT = 0x800705b4 - ERROR_TIMEOUT]. I figured that the 15 minutes might end up being a timeout period since it was consistent.
I came across a single article where someone saw something similar with a Windows 2008 R2 domain controller getting stuck at 42% and had opened a premier case with Microsoft: https://social.technet.microsoft.com/Forums/office/en-US/f8fe7d4c-af64-4e65-a007-1f557518628e/windows-2008-r2-sp1-fails-to-install-on-domain-controller-errortimeout-at-42?forum=winservergen
As a solution, they modified the registry value for BlockTimeIncrement in the Trusted Installer service key: HKLM\System\CurrentControlSet\Services\TrustedInstaller. This appears to be a timeout used for driver enumeration, and by default this is set to 15 minutes. Increasing this value from 384 (15 Minutes) to 2a30 (3 hours) gave it enough time to wait for whichever component was taking longer than 15 minutes, and eventually the update installed successfully.