Macro Code Hangs/Freezes Adding Rows

I've managed to use some code I found to add a new row below the selected row, and duplicate all the forumlas of the source row. It worked fine dozens of times yesterday, but today it's decided not to work. It gets as far as creating the new row(s), but then just hangs & excel crashes before duplicating the formulas. I've even tried reverting to an earlier version, which also worked fine, but this crashes also!

Sub Add_New_Row()
' Unlock Worksheet
Worksheets("Sheet1").Unprotect Password:="*****"
Dim x As Long
ActiveCell.EntireRow.Select 'So you do not have to preselect entire row
If vRows = 0 Then
vRows = Application.InputBox(prompt:= _
"How many rows do you want to add?", Title:="Add Rows", _
Default:=1, Type:=1) 'Default for 1 row, type 1 is number
If vRows = False Then Exit Sub
End If
'if you just want to add cells and not entire rows
'then delete ".EntireRow" in the following line
Dim sht As Worksheet, shts() As String, i As Integer
Redim shts(1 To Worksheets.Application. ActiveWorkbook. _
Windows(1).SelectedSheets.Count)..................................