Not sure if it exactly the same cause, but a large number, but not all, of our machines are suffering the same problem on Windows 10 Build 19042.928 running KES 11.6.0.394, The event-log entry for the user-profile service lists KAV as locking the user profile. Whitelisting NTUSER.dat simply changes the event log entry to ‘unspecified error’. Looking at KAV there are entries for ‘operation with application resources is blocked by Self-Defense’. Disabling Self-Defense and then deleting the (corrupted) local copy of the roaming profile allows users to log-in again. This only seems to apply to our mandatory profiles. While we can run without Self-Defense, this seems less than ideal, can anyone offer any advice?