Program hang when running outside of VS

[stanav]

Hi,
I hope someone can help explain this very weird behavior that I'm running into. I have a small program that communicates with a testing device over the serial port. The program will send some commands to the tester and receive some test data back. That test data is saved to a database and displayed on the UI. During debugging in Visual Studio 2015, everything works correctly as designed. However, when the program is released and tried to run as a standalone app, it will hang when trying to update the UI with the test data (the test data received is all valid and successfully saved to the database, but the program hangs when trying to display that data on the UI when calling "PopulateForm"). I'm stuck and unable to determine the cause of this behavior.
In summary:
- Program runs properly during debugging in VS
- It will hang when running outside of VS
- Narrow down to this line when it gets stuck: Me.BeginInvoke(New UpdateUI_Delegate(AddressOf PopulateForm))
- When the execution reaches that code line, the program becomes unresponsive and needs to be killed via task manager.

What I have tried:
- Rewrite that code line using different ways, i.e. Me.BeginInvoke(Sub() PopulateForm())... This made no difference
- Tried using Invoke instead of BeginInvoke: made no difference.
- Spinning off another thread to perform the PopulateForm task - also made no difference
- Set Form.CheckForIllegalCrossThreadCalls = False then call PopulateForm() without Invoke or BeginInvoke: this works but I try to avoid it if there is a more proper way to do it.

Here is the relevant code:

Private Delegate Sub UpdateUI_Delegate()

 Private Sub RS232_DataReceived(sender As Object, e As SerialDataReceivedEventArgs) Handles RS232.DataReceived
        If Not (e.EventType = SerialData.Eof) Then
            Dim incomingData = Me.ReadIncomingSerialData()
            If incomingData IsNot Nothing Then
                ProcessIncomingSerialData(incomingData.ToArray)
            End If
        End If
    End Sub

 Private Sub ProcessIncomingSerialData(ByVal rx_buf As Byte())
        Me.StatusUpdate("Process incoming serial data...")

        Dim x As Integer = rx_buf.Length
        Dim y As Integer = 0
        Dim crc As Byte = 0

        'code removed....

            Select Case rx_buf(0)   
                Case UPLOAD_LOG_DATA_COMMAND 

                    Me.StatusUpdate("Received UPLOAD_LOG_DATA_COMMAND")

                   'code removed...

                    Me.StatusUpdate("Reply_To_ATE(ASCII_ACK)")
       
                Case REQUEST_EE_STRING_COMMAND

                    Me.StatusUpdate("Received REQUEST_EE_STRING_COMMAND")

                   ' code removed....
                 
                Case SAVE_RECORD_COMMAND

                    Me.StatusUpdate("Received SAVE_RECORD_COMMAND")
                    ' Save data record to database
                    '         
                    If SaveDataRecords(ErrorMessage) Then
                        Me.StatusUpdate(String.Format("Data records for serial number '{0}' saved to database.", Me.lblSerialNum.Text), Color.Blue)
                        
                        Me.BeginInvoke(New UpdateUI_Delegate(AddressOf PopulateForm))

                        Reply_To_ATE(ASCII_ACK)
                        Me.StatusUpdate("Reply_To_ATE(ASCII_ACK)")

                    Else
                        Reply_To_ATE(ASCII_NACK)
                        Me.StatusUpdate("Reply_To_ATE(ASCII_NACK)", Color.Red)
                    End If

                Case UPLOAD_EE_STRING_COMMAND
                    Me.StatusUpdate("Received UPLOAD_EE_STRING_COMMAND")
                   
                   'code removed

            End Select
        Else
            Reply_To_ATE(ASCII_NACK)
            Me.StatusUpdate("Reply_To_ATE(ASCII_NACK): the value of CRC is incorrect.", Color.Red)
        End If

    End Sub

 Sub PopulateForm()

        Me.StatusUpdate("Populating form...")
        Try
            Me.lblTestDate.Text = ATEData.TestDate.ToString("G")
            Me.lblSerialNum.Text = ATEData.SerialNumber.Substring(0, SN_LENGTH)
            Me.txtVoltageSupply.Text = ATEData.Supply_Voltage.ToString("F3")
            Me.txtVoltageRawMin.Text = ATEData.MinRawTreadleVoltage.ToString("F3")
            Me.txtVoltageRawMax.Text = ATEData.MaxRawTreadleVoltage.ToString("F3")
            Me.txtVoltageRawDelta.Text = (ATEData.MaxRawTreadleVoltage - ATEData.MinRawTreadleVoltage).ToString("F3")
            Me.txtVoltageMVMMax.Text = ATEData.MaxNVMTreadleVoltage.ToString("F3")
            Me.txtVoltageNVMMin.Text = ATEData.MinNVMTreadleVoltage.ToString("F3")
            Me.txtMotorLoadLow.Text = ATEData.Low_Motor_I.ToString("F1")
            Me.txtMotorLoadMed.Text = ATEData.Med_Motor_I.ToString("F1")
            Me.txtMotorLoadHigh.Text = ATEData.High_Motor_I.ToString("F1")
            Me.txtVoltagePBReleased.Text = ATEData.PB_Released_Voltage.ToString("F3")
            Me.txtVoltagePBPressed.Text = ATEData.PB_Pressed_Voltage.ToString("F3")
            Me.txtLEDLoadX.Text = ATEData.LoadCurrentX.ToString("F1")
            Me.txtLEDLoadY.Text = ATEData.LoadCurrentY.ToString("F1")
            Me.txtLEDLoadZ.Text = ATEData.LoadCurrentZ.ToString("F1")
            Me.rtbNVMData.Text = Module1.ConvertToHexString(ATEData.NVMData)
            Me.txtCRCHeaderNVM.Text = Conversion.Hex(CRC_Data.NVM_Header)
            Me.txtCRCModuleNVM.Text = Conversion.Hex(CRC_Data.NVM_Module)
            Me.txtCRCHeaderCalculated.Text = Conversion.Hex(CRC_Data.Calculated_Header)
            Me.txtCRCModuleCalculated.Text = Conversion.Hex(CRC_Data.Calculated_Module)
            Me.dgvATETestResults.DataSource = Me._dsLinemasterSoftware.Tables("TableName")
            Me.txtSerialNumber.Select()
            Me.StatusUpdate("Finished populating form.")
        Catch ex As Exception
            Me.StatusUpdate("Failed to populate form. " & ex.Message, Color.Red)
        End Try

    End Sub