Win 10 - "Interactive Signin Process Iniitilization has failed"

Has anyone experienced and fixed this bug. It seems to be fairly common
according to the number of google matches. The absence (or corruption) of
\windows\system32\logonui.exe seems to be implicated, with a lot of fixes
being ways of copying the file from a saved version (if one exists) or else
copying from another PC. But is that the whole story?

A friend has started getting this every time he boots, with the added
peculiarity that his mouse pointer does not move, so the mouse driver seems
to be blocked as well. Restoring from a saved restore point does not work
(not sure of the symptom). Next resort (if replacing logonui.exe doesn't
help) is to try to restore to factory state, having xcopied the user data to
a backup drive (luckily Command Prompt does still work).

But before we go down that route, is there anything else to try first?


One interesting thing is that on the Microsoft forums no-one from MS has
ever acknowledged that the problem exists or offered solutions. It's the
standard response that they give to many problems, which gives the
impression that this is a new one that they've never heard of before.