another error im afraid:

System.ArguementOutOfRangeException: Index was out of range.Must be non negative and less than the size of the collection.
Parameter name: index
at System.Collections.ArrayList.get_Item(Int32 index)

i declared i as an integer(which wasnt in your code) as it wasnt recognising i,might that have somethin to do with it?

Code:
Imports System.Data


Public Class Form1

    Dim Ping As Net.NetworkInformation.Ping
    Dim pReply As Net.NetworkInformation.PingReply


    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim i As Integer
        Dim ds As New DataSet
        Dim da As OleDb.OleDbDataAdapter
        Dim sql As String
        Dim con As New OleDb.OleDbConnection

        con.ConnectionString = "PROVIDER=Microsoft.Jet.OLEDB.4.0;Data Source = C:\Documents and Settings\mhorgan\Desktop\VBtest.mdb"
        con.Open()

        sql = "SELECT * FROM tblone"
        da = New OleDb.OleDbDataAdapter(sql, con)
        da.Fill(ds, "monitor")

        Dim cb As New OleDb.OleDbCommandBuilder(da)
        Ping = New Net.NetworkInformation.Ping

        Dim dgvr As DataGridViewRow
        For i = 0 To ds.Tables("monitor").Rows.Count - 2
        Next
        dgvr = New DataGridViewRow 'Creates a new row            
        DataGridView1.Rows.Add(dgvr) 'Add the row             

        Try
       
            pReply = Ping.Send(ds.Tables("monitor").Rows(i).Item(0)) 'Sends the ping to the current item                

            DataGridView1.Rows.Item(i).Cells(0).Value = ds.Tables("monitor").Rows(i).Item(0) 'Updates the value of the new Item                

            DataGridView1.Rows.Item(i).Cells(1).Value = pReply.Status 'The value of the status returned                 

            If pReply.Status <> Net.NetworkInformation.IPStatus.Success Then 'Sets the color of the cell         

                DataGridView1.Rows.Item(i).Cells(1).Style.BackColor = Color.Red
            Else
                DataGridView1.Rows.Item(i).Cells(1).Style.BackColor = Color.Green
            End If

            ds.Tables("monitor").Rows(i).Item(1) = pReply.Status 'Write in the original datatable
            da.Update(ds, "monitor") 'Updates the database
        Catch ex As Exception
            MessageBox.Show(ex.ToString())
        End Try
        'Next
    End Sub


    Private Sub btnExit_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnExit.Click
        Dim con As New OleDb.OleDbConnection
        con.ConnectionString = "PROVIDER=Microsoft.Jet.OLEDB.4.0;Data Source = C:\Documents and Settings\mhorgan\Desktop\VBtest.mdb"
        con.Close()
        End

    End Sub


End Class