Problem as stated Above
Discovered when I recreated, from scratch,
all macros and source files, on another computer.
It locked up as before on my main computer.
By chance I tried Macro RUN, and lo an behold, it worked.
I have previously submitted a macro for the same process, but
operating differently. It also locked up after file 1.xls was
opened and would just sit there with active cell A1.

SO, how and/or why, can/does a keyboard shortcut
stop a macro from running

Sub Create_MASTER_File()
' KeyBoard ShortCut: Ctrl+Shift+ M
' ToolBar Icon: NONE
' Menu Item: NONE

Dim DestBook As Workbook
Dim mySource As Workbook
Application.ScreenUpdating = False
Application.EnableEvents = False

' Open Workbook and Save As: M2M-MASTER.XLS
Workbooks.Add
ChDir "C:\DATA"
ActiveWorkbook.SaveAs Filename:="C:\DATA\M2M-MASTER.XLS",
FileFormat:=xlNormal _
, Password:="", WriteResPassword:="", ReadOnlyRecommended:=False, _
CreateBackup:=False

' The M2M-MASTER must be (will be) the active WB when initiating macro
Set DestBook = ActiveWorkbook
Sheets(1).Activate
Set mySource = Workbooks.Open("C:\DATA\1.xls")

' 1.xls is now open and available
' Go to 1.xls, Sheet #1, Row 1, Copy
' Go to DestBook, Sheet 1, Row 1 and Insert Cut Cells

DestBook.Worksheets(1).Range("A1:IV1").Value =
mySource.Worksheets(1).Range("A1:IV1").Value

' Save only DestBook
With DestBook
.Save
End With

'Save and Close Source Book.xls
With mySource
.Save
.Close Savechanges:=True
End With

Application.EnableEvents = True
Application.ScreenUpdating = True

End Sub