Hence there is no way of reading the events from this dialog window.
It happens in some Browsers (Opera and Google Chrome) for security reasons when running the calendar from local harddisk.
It can also randomly happen when running as a Windows Desktop Gadget - Using the "Close" button here below will reset the access between the windows, which should make this dialog work when you open it again.
It requires the use of ActiveX to save and delete events. Therefore this is only possible from Microsoft Internet Explorer - or when running the calendar as a Windows Desktop Gadget.