vb.net Office Excel Interop Assembly Fails

I get the following error when trying to export my dataset to excel.  

Unable to cast COM object of type 'Microsoft.Office.Interop.Excel.ApplicationClass' to interface type 'Microsoft.Office.Interop.Excel._Application'. This operation failed because the QueryInterface call on the COM component for the interface with IID '{000208D5-0000-0000-C000-000000000046}' failed due to the following error: Library not registered. (Exception from HRESULT: 0x8002801D (TYPE_E_LIBNOTREGISTERED)).

Apparently the interop assemblies are not registered.  Failure occurs on the 'excelApp.Workbooks.Add" is executed.  I have added the reverence to Microsoft.Office.Interop.Excel (Version 12.0.0.0).  I have Office 2007 on my PC.  I have used this exact code in the past and it worked fine.  Do I need to register the asseblies again?  If so, how.  I have already repaired Office 2007 and that did not work.  I'm running Visual Studio 2008 with.net framework of 3.5

Thanks for the help.

Select Case TC_ServiceData.SelectedIndex
            Case Is = 1
                Me.Cursor = Cursors.WaitCursor
                Dim excelApp As New Microsoft.Office.Interop.Excel.Application()
                Dim excelBook As Microsoft.Office.Interop.Excel.Workbook = excelApp.Workbooks.Add
                Dim excelWorksheet As Microsoft.Office.Interop.Excel.Worksheet = _
                    CType(excelBook.Worksheets(1), Microsoft.Office.Interop.Excel.Worksheet)
                excelApp.Visible = False

                With excelWorksheet
                    'Creates connections to pull data to DataSet

                    Dim dr As DataRow
                    Dim i As Integer = 2
                    .Range("A1").Value = "TECHNICIAN"
                    .Range("A1").Font.Bold = True
                    .Range("A1").ColumnWidth = 15
                    .Range("B1").Value = "CALL DAY"
                    .Range("B1").Font.Bold = True
                    .Range("B1").ColumnWidth = 15
                    .Range("C1").Value = "TIME"
                    .Range("C1").Font.Bold = True
                    .Range("C1").ColumnWidth = 15
                    .Range("C1").Value = "STATUS"
                    .Range("C1").Font.Bold = True
                    .Range("C1").ColumnWidth = 15
                    .Range("C1").Value = "CALL NUMBER"
                    .Range("C1").Font.Bold = True
                    .Range("C1").ColumnWidth = 15
                    .Range("C1").Value = "CUSTOMER"
                    .Range("C1").Font.Bold = True
                    .Range("C1").ColumnWidth = 50

                    'Populate Excel spreadsheet
                    Try
                        For Each dr In mDataSet.Tables(0).Rows

                            .Range("A" & i.ToString).Value = dr("controlId")
                            .Range("B" & i.ToString).Value = dr("orderId")
                            .Range("C" & i.ToString).Value = dr("pickupDate")
                            i += 1


                        Next
                    Catch ex As Exception
                        Me.Cursor = Cursors.Default
                        MessageBox.Show(ex.Message)
                    End Try
                    'Make Excel visible
                    excelApp.Visible = True
                    Me.Cursor = Cursors.Default
                End With
                Me.Cursor = Cursors.Default
            Case Is = 1


        End Select

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