Form Load and CheckChange Events at times fire and not fire.

in my experience, changing the checkbox from form load doesnt throw the event....

so you may want to move all the code into a separate (eg) chkTPCalcActions function, which is called from _CheckedChanged

in that way, you can set the checkbox on form load (from a previous settings or similar) and then call the chkTPActions to do other updates

OK, but where do I put my function if I move it outside the event?

same code file,

Private Sub chkTPCalcActive_CheckedChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles chkTPCalcActive.CheckedChanged

        chkTPCalcActions()
end Sub

Sub chkTPCalcActions()
        Dim GageConfiguration As String
        If TPFormLoaded = True Then
            TPFormLoaded = False
            Exit Sub
        End If
        If Me.chkTPCalcActive.Checked = True Then
            ' If TPCalcSwitchState = True Then
            ActivateTPCalculation = True
            TPCalcSwitchState = True
            GageConfiguration = ("<@:L" & GageID & "08<GAGE,P>")
            serialCOMDiscover.WriteLine(GageConfiguration)
            System.Threading.Thread.Sleep(1000)
            'ElseIf TPCalcSwitchState = True or  Then
            'ActivateTPCalculation = False
            'GageConfiguration = ("<@:L" & GageID & "08<GAGE,P>")
            'serialCOMDiscover.WriteLine(GageConfiguration)
            'System.Threading.Thread.Sleep(1000)
            ' End If
            'TPCalcSwitchState = True
        ElseIf Me.chkTPCalcActive.Checked = False Then
            ActivateTPCalculation = True
            TPCalcSwitchState = True
            GageConfiguration = ("<@:L" & GageID & "08<GAGE,P>")
            serialCOMDiscover.WriteLine(GageConfiguration)
            System.Threading.Thread.Sleep(1000)
        End If
    End Sub

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After taking a closer look on how to handle the event. I was able to set a flag on the form load event so if the event from the radio button was raised it would look to see if the form has been entered or not.