Logon Screen Flashing / Busy

Problem with the logon screen with windows 10. I upgraded on the morning of Saturday 8th August, without any serious problems. However, later on in the afternoon, I had to do a restart, after a virus/malware scan and removal of infections. The OS was updated at this point, after which a serious problem occurred. Once the OS reached the logon screen, it started flashing on and off between Logon screen and time/date start up picture, with the cursor showing busy. It also reported an error message to do with LogonUI .

I had no way to Logon, or to open task manager, so i had to boot into safe mode, and attempt various problem solving solutions read elsewhere for this issue on the net. None of these worked, so i had to roll back to Windows 7 for the time being. Should i upgrade again, this issue will have to be resolved.

Finally, though, i'm led to believe that LogonUI is malware, and not an important system file, but should it be removed, would this be the cause of the issue?