upgrading to PS CC 2015.5 (Windows 10 64-bit), PS was no longer
loading. First it asked me whether I wanted to run it (as if it were a downloaded file) and then it issued an error 16 (configuration error) and asked me to uninstall / reinstall.
I uninstalled / reinstalled twice and each time Windows 10 freezed after the end of the installation. Only a hard reset could help. Reinstalling didn't fixed the problem anyway.
The only way to fix this is to modify the properties of photshop.exe and to check "run as administrator" in Compatibility tab.
There's a document discussing this issue : http://helpx.adobe.com/x-productkb/policy-pricing/configuration-error-cs5.html . Solution #1 is what I described above. Solution #2 doesn't work and is dependent on specific UAC settings anyway.
Note that there were no such problems with PS CC 2015.1.
Also, during the update, user presets and actions are not transferred as well as the installed plugins. You have to do this manually.
Sigh! Fed up with these permanent update problems.