Simple sort code hides row 47 randomly!

[MOB]

Sub ResNoSort()

lastRow = Cells(Rows.Count, 1).End(xlUp).Row - 1

    ActiveSheet.Unprotect Password:="password"
    Rows("6:" & lastRow).Select
    ActiveSheet.Sort.SortFields.Clear
    ActiveSheet.Sort.SortFields.Add Key:=Range("B6:B" & lastRow) _
        , SortOn:=xlSortOnValues, Order:=xlAscending, DataOption:=xlSortNormal
    With ActiveSheet.Sort
        .SetRange Range("A6:EZ" & lastRow)
        .Header = xlGuess
        .MatchCase = False
        .Orientation = xlTopToBottom
        .SortMethod = xlPinYin
        .Apply
    End With
    Range("B6").Select
    ActiveSheet.Protect Password:="password", AllowFormattingCells:=True
End Sub

When I run the above code, sometimes(!) it changes the row height of row 47 to zero...................

I cant replicate it reliably, and I have amended the code to reset the row height now, but any ideas why this could be, or is it just a bug?

TIA

 

[Fluff]

Only thing I can think of is that you might have some event code on that sheet.