same problem as above.
I started with a fresh install of windows 8. Waiting for windows update to install all updates which took 36 hours. Started 8.1 update from the windows store app icon. Downloads in normal time, installing seems normal, then sits on Applying changes 63%. Left it over night, made sure PC didnt sleep or hibernate and it was still stuck.
All drivers are updated, no programs installed except for firefox. Using an admin account. Ran Windows 8.1 upgrade assist with no incompatible programs or hardware. What do?