Sub Auto_Open()

Dim SaveAsName As String
Dim strDocName As String
Dim intPos As Integer

strDocName = ActiveWorkbook.Name
intPos = InStrRev(strDocName, ".")
strDocName = Left(strDocName, intPos -  1 )
strDocName = strDocName & ".txt"
 
SaveAsName = ActiveWorkbook.Path & Application.PathSeparator & strDocName
ActiveWorkbook.SaveAs Filename:=SaveAsName, FileFormat:=xlText, _
        ReadOnlyRecommended:=False, CreateBackup:=False
ActiveWindow.Close

Method 'SaveAs' of object '_Workbook' failed

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