I have the same problem.
Enviro is Windows7 x64 clean(ish) build (it has Office 2013 but not much else).
I built a package using Adobe Package manager, to install most of CC.
It runs OK, kills Exporer.exe, then seems to stop.
I get Error 10007 in the Event Log, from "Restart Manager", saying "Application or service 'Windows Explorer' could not be restarted."
Then nothing happens, the progress bar freezes and Explorer never restarts.
Remote tasklist shows that the relevant msiexec process is still running, with low and slowly increasing memory usage.
I will leave this machine for a couple of hours to see if anything changes; I believe from earlier tests that the CC install is actually done, if I force-reboot now it will all work.
Not a satisfactory situation though.