I have an MFC (C++) application that creates an MS Access database from messages contained in text files. This code has been around for a long time and not changed very much. I have a situation in processing a large text file where I'm getting an IDispatch Error #3105 with a description of "invalid argument". The error occurs when calling the Update() call on the ADO Recordset object. The thing is, this error occurs after some 3 million messages have already been successfully processed, and when I try to debug the program, I don't see what might be causing this error. Does anyone have any ideas? Is there a way to step into the Update() call to actually see what is going on in there?