Vb .net timer problem with Windows 7 dual processors

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I have been writing visual basic and vb .net applications for years and have come across this problem while upgrading from Windows Xp to Windows 7.

 

First let me explain the application then what it does on 4 different computers, the hardware and software I used. The application is written in Visual Studio 2005 VB .net framework 2. I is a very simple photo timer program that allows you to set a time in hours, minutes and seconds the start a count down to 0 that will play a sound file.

I use 2 timers, timer1 is set to an interval of 1000 and updates the count down text every second. Timer2 is set to the interval of the time for the counter, for example a 1 minute time is an interval of 60000. I checked the running of timer2 with a clock and it works fine. However timer1 will be behind by increasing amounts as the program runs. It will always be slow by 6 seconds in 500 seconds for example. This only happens on Windows 7 with a dual processor system.

Here is what works and does not work.

 

Windows Xp works always, even when running virtual pc under Windows 7.

Windows 7 works on Pentium 4 system.

Windows 7 fails on Pentium E6500 dual core system.

Windows 7 fails on IBM Lenovo R61i Pentium dual core T2370.

 

I wrote a simpler test program and it does the exact same thing.

Changed the timer to system.timer. timer and it did not change the problem.

 

Here is the code with the system.timer

 

Public Class Form1

 

Dim I = 0

Dim Running As Boolean = False

 

Private t As New System.Timers. Timer(1000)

 

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load#

AddHandler t.Elapsed, AddressOf TimerDone

t.Interval = 1000

t.SynchronizingObje ct = Me

 

End Sub

 

Public Sub TimerDone(ByVal sender As Object, ByVal e As System.Timers. ElapsedEventArgs )

I = I - 1

Label1.Text = I

 

End Sub

 

Private Sub Button1_Click( ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

If Running = False Then

Label2.Text = ""

Button1.Text = "Stop"

TrackBar1.Enabled = False

Timer2.Interval = Label1.Text * 1000

I = (Timer2.Interval / 1000) - 1

t.Enabled = True

Timer2.Enabled = True

Running = True

Else

'Timer1.Enabled = False

Timer2.Enabled = False

t.Enabled = False

TrackBar1.Enabled = True

Button1.Text = "Start"

Label2.Text = "Stopped"

Running = False

End If

 

End Sub

 

Private Sub Timer2_Tick( ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer2.Tick

Timer1.Enabled = False

Timer2.Enabled = False

t.Enabled = False

Button1.Text = "Start"

I = 0

Label2.Text = "Done"

TrackBar1.Enabled = True

Button1.Text = "Start"

Running = False

 

End Sub

 

Private Sub TrackBar1_Scroll( ByVal sender As System.Object, ByVal e As System.EventArgs) Handles TrackBar1.Scroll

Label1.Text = TrackBar1.Value

 

End Sub

 

End Class

 

Thanks for any ideas.