log-in annoyance

After the Creators Update,the password is deemed to be "incorrect".Following a restart,the same password is accepted and all is normal.
I have tried ----dism /online /cleanup-image /restorehealth and sfc /scannow and both returned clear report.Next thing was Credential manager,right clicked and restart.
No change.
All I can think of now is either put up with the annoyance or the dreaded Clean install.
If anyone has a suitable fix for this,it would be gratefully received.
The prospect of doing yet another clean install is off putting.
Joe

Thanks dencal,but that doesn't fix the problem of why a restart is the only way the password is accepted.It is only the initial log-in which rejects it.If I cancel the log-in requirement through User account,needless to say there is no problem,which is the same as removing the front door because a lock doesn't work,everyone has access.
I've only had the Creators Up-date for a few days,so some fix might appear-----ever hopeful.

The cause was the CU resetting Fast Startup to operate.Not long after the installation of Win10,I had unchecked Fast Startup and very infrequently had a look to see if it had changed.It is now unchecked once again and so far all is normal