Superdupe

Sounds like this one: https://answers.microsoft.com/en-us/msoffice/forum/msoffice_officeinsider-mso_win10/officebackgroundtaskhandlerregistration-flashes-a/2600497e-78e4-41a1-9040-461cd2c3ea13 I fixed it by deactivating the task in Task Scheduler, as suggested on the Microsoft forums.