Match Sheets code error

[zakasnak]

I have a MatchSheets code that I got from this board:
http://www.mrexcel.com/forum/showthread.php?t=370741

I have run into an issue, but I'm wondering if it's because of the number of sheets I'm trying to match?

Sub MatchSheets()
    Dim openName As String
    Dim firstWB As String
    Dim secondWB As String
    Dim firstSheet As String
    Dim secondSheet As String
    Dim sa As String
    Dim x As Integer, i As Integer
 
    firstWB = ActiveWorkbook.name
    openName = Application.GetOpenFilename("Excel Workbook (*.xls), *.xls")
    Workbooks.Open (openName)
    secondWB = ActiveWorkbook.name
 
    Workbooks(firstWB).Activate
 
    For i = 1 To ActiveWorkbook.Sheets.Count
        firstSheet = Sheets(i).name
        Workbooks(secondWB).Activate
        For x = 1 To ActiveWorkbook.Sheets.Count
            secondSheet = Sheets(x).name
            If firstSheet = secondSheet Then
                Workbooks(firstWB).Activate
                Sheets(i).Select
                Range(Range("A2"), Range("A65536").End(xlUp)).EntireRow.Copy  'if there are headers to skip change "A1" to first Row with data i.e. "A2" or "A5"
                Workbooks(secondWB).Activate
                Sheets(x).Select
                Range("A65536").End(xlUp).Offset(1, 0).Select
                ActiveSheet.Paste
                Exit For
            ElseIf x = ActiveWorkbook.Sheets.Count And firstSheet <> secondSheet Then
                Workbooks(firstWB).Activate
                [COLOR=red][B]Sheets(i).Copy After:=Workbooks(secondWB).Sheets(x) 'this will copy unique sheets from the first Workbook to the end of the second Workbook[/B][/COLOR]
                Workbooks(secondWB).Activate
            End If
        Next
        Workbooks(firstWB).Activate
    Next
 
End Sub

I'm getting this error on the same sheet every time I run it.... maybe it's because of the sheet name, but I don't know:

Run-time error '-2147417848 (80010108)':
Automation error
The objectinvoked has disconnected from its clients

Hitting debug highlights the line in red above. This code works correctly, except on this project.... could it be the number of sheets?