If you're seeing this message after snoozing or dismissing a reminder and this is for a calendar you do not want to add or edit events for, you can mark this calendar as read-only to avoid such experience in future. To do so, get to the calendar properties by right-clicking on this calendar in the list in the calendar or task view.
Si tu vide iste message post le prorogation o le clausura de un memento e isto es pro un agenda pro le qual tu non vole adder o rediger eventos, tu pote marcar iste agenda como sol lectura pro evitar simile experientia in futuro. Pro facer assi, procura al agenda proprietates per cliccar dextre sur iste agenda, in le lista del agenda o in le vista del activitates.