RobiNew,
Firstly, what is LastChr? It is not declared as a variable.
Secondly, if it is intended as a range, then stop treating it like a selection.
Code:
Sub ScratchMacro()
'A basic Word Macro coded by Gregory K. Maxey
Dim oRng As Range
Set oRng = ActiveDocument.Range
oRng.Collapse wdCollapseEnd
oRng.Start = oRng.Start - 1
oRng.Font.Underline = wdUnderlineNone
oRng.InsertAfter vbCr & "First Part - End"
lbl_Exit:
Exit Sub
End Sub