Just another way to skin the cat


Sub FindWrkBk(PathToWorkbook As String, WrkBook As String)
    Dim IsThere As Boolean
    Dim Wrkbk As Workbook
    IsThere = False
    For Each Wrkbk In Workbooks
    If Wrkbk.Name = WrkBook Then
        IsThere = True
    End If
    Next
    If Not IsThere Then
    Application.Workbooks.Open PathToWorkbook & "\" & WrkBook
    End If
End Sub

Sub does()
FindWrkBk "C:\WINDOWS\Desktop\stuff", "class.xls"
End Sub