Mathcad Events

In the Mathcad API, about a dozen events are exposed in the IMathcadPrimeEvent2 interface, including "OnWorksheetModified" and "OnWorksheetSaved". I am attempting to access the IMathcadPrimeWorksheet3 property "Modified" within these events. However, when I try to get or set this property within the event, the Mathcad worksheet/application completely freezes and does not allow the code to proceed with getting or setting this property. What's up with that? Is there any way around this? 

The reason I am trying to get at this "Modified" property is because, for some reason, the worksheet is only considered "modified" the first time after a save, or when saving. Not sure why this was the case.