The simple way is to just count the total datetime then add it on a CountDownBox on properties then you will need to trace the shutdown events so that even if you close the program but it will keep a record of the last count before it shutdown so when you re-run it, it will then read the time from the disc. but let me first show you how I done this all. let say you want to count the 24Hours so if your timer will fire in minutes (1000) interval then here is how you count it. We know that you will be using the minutes so you start from 1000 x 60 x 24 = 1440000 so you will put the 1440000 to the properties of the CountDownBox then on your timer interval should be 1000 not 100 unless you counted from 100 not 1000 and your timer code will be like this
Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick
CountDownBox.Text = CountDownBox.Text - 1
If CountDownBox.text = 0 Then
Timer1.stop()
Else
' Do Nothing ather then Counting down
CountDownBox.Text = CountDownBox.Text - 1
End If
End Sub
then you have to track the shutdown events so that when you have close and rerun it wont start over and over again when ever you re-run the program. Hope I answered your Question.