VBA Code to Zoom Data Validation Drop Down Menu Won't Work in Protected Sheet

Try
UnProtect immediately below
If Intersect.....
Protect immediately above
Exit Sub

It would be easier to read your code if you indent things - then can work out what belongs together...like this ...

With Sheet(X)
   If a = b Then
      Do something
   Else
      Do something
   End If
End With

I usually include a line at the beginning of most of my selection change event macros

If Selection.CountLarge > 1 Then Exit Sub

This can prevent problems if you select a large number of cells