NSPersistentDocument not saving after exception

Hi, My CoreData app (under 10.4) refuses to save the document once an exception has been thrown. Its a C++ exception thrown from a menu command after displaying an alert and it is caught. It happens both on Intel and PPC, in Debug and in Release mode. What happens after the exception, is

CoreData NSTextView changes: not noticed with KVO, not accessible from program, but stored anyway

ad from the file, not the text that is visible in the text field. Also, attempts to get a notification upon change don't work: [[grammarController selection] addObserver:self forKeyPath:@"text" options:0 context:0] Does anyone have a clue