The Active Investigator checkbox in a user’s profile is what determines if they are available in pick lists within the modules when creating new records or adding personnel to an existing record. When this is checked, the user will be selectable in a module. The user will always be selectable in the administration area regardless of the setting of this checkbox.
Also, the Validated checkbox in a users profile, can control if the user is allowed to log into the system. This is only relevant if the setup in Personnel Admin –> Profile Management –> Profile Creation Options –> “Allow users to log into the system without validation after the profile is created?” is set to No. If the setup is set to No and the users profile does not have the checkbox checked, then they will not be able to log into the system.