Hi,

We have an aspx page where the code behind calls a third-party COM object through an Interop dll. Usually the code executes with no problem, but every once in a while (average once a week), we get a System.NullReferenceException thrown at System.Runtime.InvokeDispMethod (stack trace below). If we try to reproduce this behavior, we are unable to -- the page works fine on the next try.

Does anyone have any idea as to why we might get an occasional NullReferenceException at this level, and one that's impossible to reproduce when exactly the same user input is given? This occurs on both .Net Framework 1.0 and 1.1 machines.

Thanks,
Leslie

1) Exception Information
*********************************************
Exception Type: System.NullReferenceException
Message: Object reference not set to an instance of an object.
TargetSite: System.Object InvokeDispMethod(System.String,
System.Reflection.BindingFlags, System.Object, System.Object[],
Boolean[], Int32, System.String[])
HelpLink: NULL
Source: mscorlib

StackTrace Information
*********************************************
   at System.RuntimeType.InvokeDispMethod(String name, BindingFlags
invokeAttr, Object target, Object[] args, Boolean[] byrefModifiers,
Int32 culture, String[] namedParameters)
   at System.RuntimeType.InvokeMember(String name, BindingFlags
invokeAttr, Binder binder, Object target, Object[] args,
ParameterModifier[] modifiers, CultureInfo culture, String[]
namedParameters)
   at System.RuntimeType.ForwardCallToInvokeMember(Strin g memberName,
BindingFlags flags, Object target, Int32[] aWrapperTypes, MessageData&
msgData)
   at PETOCXLib.PETOCXClass.SetHeaderMultilineText(Strin g FontName,
Single FontSize, Single X, Single Y, Single Width, Single Height,
String Text, Int16 Alignment)
   at BTA.EPM.Utilities.PDFStampHelper.PDFStampHelper.St ampPDF()
   at PDFStamper.PageData.StampPDF()
   at PDFStamper.PDFStamp.Button1_Click(Object sender, EventArgs e)