Consider the following scenario :-
- You have an Excel add-in (VBA, COM or VSTO) that captures the WorkbookOpen event and makes Object Model calls into Excel from this event handler.
- You open a Workbook in protected view (because of opening workbook from Internet, email attachment etc...) and click on "Enable Editing."
- Some Object Model calls (e.g. Sheet.Activate) being made from the WorkbookOpen event handler fail with a runtime error 1004 - Method of Object failed.