John,
I am getting a runtime error 3265 Item not found in the collection.

Parameters for query:
[Forms]![frmCIOC]![Open]

[Forms]![frmCIOC]![Closed]      >=[Forms]![frmCIOC]![StartDate] And
<=[Forms]![frmCIOC]![EndDate]

Revised code
Private Sub cmdStatus_Click()

Dim db As DAO.Database
Dim qdf As DAO.QueryDef
Dim rpt As Report
Dim rst As DAO.Recordset
Dim objExcel As Excel.Application
Dim wkb As Workbook
Dim wks As Worksheet
Dim s As Object
Dim i As Integer
Dim j As Integer
Dim intMaxCol As Integer
Dim intMaxRow As Integer

Set db = CurrentDb()
Set qdf = db.QueryDefs("qryCIO")
With qdf
   .Parameters("Open").Value = Forms("frmCIOC").Controls("Open").Value
   .Parameters("Closed").Value = Forms("frmCIOC").Controls("Closed").Value
And .Parameters("StartDate").Value =
Forms("frmCIOC").Controls("StartDate").Value And .Parameters("EndDate").Value
= Forms("frmCIOC").Controls("EndDate").Value

  ' .Parameters("StartDate").Value =
[Forms]![frmCIOC].Controls("StartDate").Value And
.Parameters("EndDate").Value = [Forms]![frmCIOC].Controls("EndDate").Value
End With
Set rst = qdf.OpenRecordset

With rst
intMaxCol = rst.Fields.Count
 If rst.RecordCount > 0 Then
   rst.MoveLast:    rst.MoveFirst
   intMaxRow = rst.RecordCount
   Set objExcel = New Excel.Application
   With objExcel
     .Visible = True
     Set wkb = .Workbooks.Add
     Set wks = wkb.Worksheets(1)
     With wks
       .Range(.Cells(2, 1), .Cells(intMaxRow, _
           intMaxCol)).CopyFromRecordset rst
     End With
   End With
 End If

End With
Set objExcel = Nothing
Set wkb = Nothing
Set wks = Nothing
'Set s = Nothing

End Sub