If the "Enabled privileged operations" checkbox is ticked in the "Advanced" tab of File->Preferences, the OT will prompt for a username and password every time the OT is started and, upon failure, report that this option is being disabled. "Privileged operations" are only available to persons within the ALMA project who have special access privileges. To stop the prompts, untick the checkbox. Privileged operations are not required for the preparation and submission of an ALMA proposal.