Which action can throws this COMException?

Hi there,

sometimes and not really reproducible I get the following COMException:

System.Runtime.InteropServices.COMException (0x800706BE): The remote procedure call failed. (Exception from HRESULT: 0x800706BE)
at System.RuntimeType.ForwardCallToInvokeMember(String memberName, BindingFlags flags, Object target, Int32[] aWrapperTypes, MessageData& msgData)
at InDesignServer._Application.get_Documents()
at MyApplication.openDocument(String filename)
at [...]

As you can see, the exception is thrown anywhere behind my openDocument function. Since the error occurs only sometimes I want to know which action (method call, property access, whatever) makes use of InDesignServer._Application.get_Documents()?

These are the accesses I do on the COM-application:
InDesignApp.Open(theFilename)
ActiveDocument = InDesignApp.Documents.FirstItem
ActiveDocument.ViewPreferences.HorizontalMeasurementUnits = idMeasurementUnits.idMillimeters
ActiveDocument.ViewPreferences.VerticalMeasurementUnits = idMeasurementUnits.idMillimeters
ActiveDocument.Converted
ActiveDocument.Save(theFilename)
InDesignApp.Documents.Count
InDesignApp.Documents.LastItem.Close(InDesignServer.idSaveOptions.idNo)

So which one is the suspect?
I think this can only be answered by the Adobe crew...