I think the message box at the start needs to be a bit more complex to deal with the likely selections: less than two paragraphs; includes a table
Code:
Sub ReverseOrderOfParagraphs()
Dim tmpTable As Table, rg As Range
If Selection.Range.Paragraphs.Count < 2 Then
MsgBox "You must select more than one paragraph"
Exit Sub
ElseIf Selection.Range.Tables.Count > 0 Then
MsgBox "This macro doesn't work with selections which are in tables"
Exit Sub
End If
Set tmpTable = Selection.Range.ConvertToTable(Separator:=wdSeparateByParagraphs)
With tmpTable
.Columns.Add BeforeColumn:=.Columns(1)
Set rg = .Cell(1, 1).Range
rg.End = rg.End - 1
rg.Fields.Add Range:=rg, Type:=wdFieldSequence, Text:="a"
rg.Cells(1).Range.Copy
.Columns(1).Select
Selection.Paste
Selection.Fields.Update
.Sort ExcludeHeader:=False, FieldNumber:=1, SortOrder:=wdSortOrderDescending
.Columns(1).Delete
.ConvertToText
End With
End Sub