i was able to get the sample running using your source code, but after waiting for 250 points to appear, i didn't see any error messages using both the release build (7.2.20072.1000) and the latest source code for 7.2.

what is the complete (4-part) version number of the Infragistics dlls you're using?

<Window
 xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
 xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
 x:Class="ChartBugTest.Window1"
 x:Name="Window"
 Title="Window1"
 Width="640" Height="480" xmlns:igCA="http://infragistics.com/Chart" xmlns:igDP="http://infragistics.com/DataPresenter" xmlns:ChartBugTest="clr-namespace:ChartBugTest">

 <Grid x:Name="LayoutRoot">
  
  <ChartBugTest:UCChart Margin="10,10,10,10" x:Name="Chart1"/>
  
 </Grid>
</Window>

------------------end--------------------------

-----window1 code behind ------------------

using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Shapes;
using System.ComponentModel;
using System.Timers;
using System.Windows.Threading;
using Infragistics.Windows.Chart;
namespace ChartBugTest
{
 /// <summary>
 /// Window1.xaml 的互動邏輯
 /// </summary>
 public partial class Window1 : Window
 {
      

  public Window1()
  {
   this.InitializeComponent();
           
   // 在此點下方插入建立物件所需的程式碼。
          
  }

      
 }
}

----------------end ---------------------------

--- UCChart.xaml usercontrol xaml code------------

<UserControl
 xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
 xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
 xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
 xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
 mc:Ignorable="d"
 x:Class="ChartBugTest.UCChart"
 x:Name="UserControl"
 d:DesignWidth="640" d:DesignHeight="480" xmlns:igCA="http://infragistics.com/Chart" xmlns:igDP="http://infragistics.com/DataPresenter">

 <Grid x:Name="LayoutRoot">
  <igCA:XamChart Margin="136,8,192,198" x:Name="TempMeter1Chart">
  <igCA:XamChart.Caption>
        <igCA:Caption Text="Temperature"/>
       </igCA:XamChart.Caption>
  </igCA:XamChart>     
  <igDP:XamDataGrid  AutoFit="True" Margin="136,0,192,22" VerticalAlignment="Bottom" Height="160" x:Name="DataDisplay" DataSource="{Binding Path=CurrentValue, Mode=TwoWay}" />
 </Grid>
</UserControl>

-------------------end---------------------

---UCChart.xaml code behind ----------------------

using System;
using System.Data;
using System.Collections.Generic;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
using System.ComponentModel;
using System.Timers;
using System.Windows.Threading;
using Infragistics.Windows.Chart;
namespace ChartBugTest
{
 /// <summary>
 /// UCChart.xaml 的互動邏輯
 /// </summary>
 public partial class UCChart
 {
        BoundObject bo = new BoundObject();
        private Random _random = new Random();
        private DispatcherTimer _timer = new DispatcherTimer();
        private DataSet ds = new DataSet();
        private DataTable dt = new DataTable("datatable");

        private DataSet cds1 = new DataSet();
        private DataTable cdt1 = new DataTable("datatable");

        private Series s1 = new Series();

        private string t = "";
        private int ct1 = 0;

  public UCChart()
  {
   this.InitializeComponent();
            StartGauge();
  }

        public void StartGauge() //必須判斷是否已經執行過
        {
            if (!_timer.IsEnabled)
            {
                _timer.Interval = new TimeSpan(0, 0, 0, 0, 1500);
                _timer.Tick += new EventHandler(_timer_Elapsed);
                Loaded += new RoutedEventHandler(IAmLoaded);
                bo = new BoundObject { CurrentValue = 11, CurrentValue1 = 5, CurrentValue4 = 10332 };
                DataContext = bo;
                _timer.Start();

                InitialTable();
                InitialChart();
                InitialChartData();
            }
        }

        /// <summary>
        /// On load show value
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        void IAmLoaded(object sender, RoutedEventArgs e)
        {
            SetValues();

        }

        void _timer_Elapsed(object sender, EventArgs e)
        {
            try
            {
                SetValues();
                BindToChart();
                BindToGrid();
            }
            catch (Exception err)
            {
                MessageBox.Show(err.Message + "..and.. the currentvalue is:" + bo.CurrentValue);
            }

        }

        /// <summary>
        /// Set the value and display
        /// </summary>
        private void SetValues()
        {

            int thevalue = _random.Next(40);
            int thewetvalue = _random.Next(10);
            if (thevalue >= 10)
            {
                bo.CurrentValue = thevalue;
                do
                {
                    thewetvalue = _random.Next(10);
                }
                while (thewetvalue < 3);
                bo.CurrentValue1 = thevalue - thewetvalue;
                bo.CurrentValue2 = thevalue + 1;
                bo.CurrentValue3 = bo.CurrentValue2 - 3;
            }

            int airpressure = _random.Next(10340);
            if (airpressure >= 100)
            {
                bo.CurrentValue4 = airpressure;
            }

            t = DateTime.Now.ToString("hh:mm:ss:tt");

        }
        private void InitialTable()
        {
            dt.Columns.Add("count", typeof(Int32));
            dt.Columns.Add("time", typeof(string));
            dt.Columns.Add("temperature", typeof(Int32));

            ds.Tables.Add(dt);
            DataDisplay.DataSource = ds.Tables["datatable"].DefaultView;
        }
        private void InitialChart()
        {
            TempMeter1Chart.Caption.Text = "Temperature Chart";
            TempMeter1Chart.Visibility = Visibility.Hidden;

        }

        private void InitialChartData()
        {
            //---Chart1 -------------------------------
            cdt1.Columns.Add("count", typeof(Int32));
            cdt1.Columns.Add("temperature", typeof(Int32));
            cds1.Tables.Add(cdt1);

            s1.DataSource = cds1.Tables["datatable"];
            s1.DataMapping = "temperature";
            s1.ChartType = ChartType.Spline;

            TempMeter1Chart.Axes.Clear();

            Axis primAxisX1 = new Axis();
            primAxisX1.AxisType = AxisType.PrimaryX;
            primAxisX1.AutoRange = true;
            TempMeter1Chart.Axes.Add(primAxisX1);

            Axis primAxisY1 = new Axis();
            primAxisY1.AxisType = AxisType.PrimaryY;
            primAxisY1.AutoRange = true;
            primAxisY1.Unit = 3;

            TempMeter1Chart.Axes.Add(primAxisY1);

            if (!TempMeter1Chart.Series.Contains(s1))
            {
                TempMeter1Chart.Series.Add(s1);
            }

            //----- end of Chart1 -------------------

        }

        private void BindToGrid()
        {
            DataRow dr = dt.NewRow();
            dr["count"] = ct1;
            dr["time"] = t;
            dr["temperature"] = bo.CurrentValue;

            dt.Rows.Add(dr);
            ds.AcceptChanges();
            DataDisplay.DataItems.Insert(0, dr);
        }

        private void BindToChart()
        {

            //--- Chart1 -----------------
            DataRow dr1 = cdt1.NewRow();
            dr1["count"] = ct1++;

            dr1["temperature"] = bo.CurrentValue;
            cdt1.Rows.Add(dr1);
            TempMeter1Chart.RefreshEnabled = true;

            if (ct1 > 1)
            {
                TempMeter1Chart.Visibility = Visibility.Visible;
            }
            //---- end of chart1 --------------------------------

        }

    }

    #region data bound class
    /// <summary>
    /// Class to do an example binding
    /// </summary>
    public class BoundObject : INotifyPropertyChanged
    {
        private double _currentValue;
        private double _currentValue1;
        private double _currentValue2;
        private double _currentValue3;
        private double _currentValue4;

        /// <summary>
        /// Current vlaue property, raises the on property changed event
        /// </summary>
        public double CurrentValue
        {
            get { return _currentValue; }
            set
            {
                _currentValue = value;
                OnPropertyChanged("CurrentValue");
            }
        }
        /// <summary>
        /// Current vlaue property, raises the on property changed event
        /// </summary>
        public double CurrentValue1
        {
            get { return _currentValue1; }
            set
            {
                _currentValue1 = value;
                OnPropertyChanged("CurrentValue1");
            }
        }

        /// <summary>
        /// Current vlaue property, raises the on property changed event
        /// </summary>
        public double CurrentValue2
        {
            get { return _currentValue2; }
            set
            {
                _currentValue2 = value;
                OnPropertyChanged("CurrentValue2");
            }
        }
        /// <summary>
        /// Current vlaue property, raises the on property changed event
        /// </summary>
        public double CurrentValue3
        {
            get { return _currentValue3; }
            set
            {
                _currentValue3 = value;
                OnPropertyChanged("CurrentValue3");
            }
        }
        /// <summary>
        /// Current vlaue property, raises the on property changed event
        /// </summary>
        public double CurrentValue4
        {
            get { return _currentValue4; }
            set
            {
                _currentValue4 = value;
                OnPropertyChanged("CurrentValue4");
            }
        }

        #region INotifyPropertyChanged Members

        /// <summary>
        /// One of my properties has changed
        /// </summary>
        public event PropertyChangedEventHandler PropertyChanged;

        /// <summary>
        /// Notify any listeners that a property has changed
        /// </summary>
        /// <param name="propName">Name of the property</param>
        protected virtual void OnPropertyChanged(string propName)
        {
            if (PropertyChanged != null)
            {
                PropertyChanged(this, new PropertyChangedEventArgs(propName));
            }
        }

        #endregion
    #endregion
 }
}

---------------------end ----------------------------

Hope this sample is helpful for bug resolved.

Sincerely,

                    Daniel Lee 2009/3/5

i was able to reproduce the problem in the latest build using your code.  i have entered it as a bug, # 15099.  it will be resolved in a future hotfix.  feel free to contact infragistics developer support at any time (http://infragistics.com/gethelp) to inquire about the status of this bug report.