An unhandled exception of type 'System.NullReferenceException' occurred in system.windows.forms.dll

Hi,

I am using the following code to open a new form...

There is an Opendialogue box that opens a file.. a sub reads the file and if an error is detected it opens a new form.

If I click on a save function on the new form the app crashed with the above error or if I close it normally and then click on the Open button on the main form again it causes the same error. Any Ideas?

Many Thanks,

Josh

Code:
Private Sub cmdOpen_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdOpen.Click
        Dim Item As String
        Dim diag As New OpenFileDialog
        Try
            diag.Filter = "All files (*.*)|*.*|Comman Seperate Vaules (*.csv)|*.csv|Text Files (*.txt)|*.txt"
            diag.FilterIndex = 2
            diag.Multiselect = True
            diag.ShowDialog()
            For Each Item In diag.FileNames
                If InStr(Item.ToLower, ".csv") > 0 Then
                    AddCSV(Item)
                ElseIf InStr(Item.ToLower, ".txt") > 0 Then
                    AddTxt(Item)
                End If
            Next
            diag.Dispose()
            diag = Nothing
        Catch ex As Exception
            MsgBox("Error!!!: " & ex.ToString, MsgBoxStyle.Critical, "Error")
        End Try
        SetCountLabel(lblCountImport, lstUsers, False)
    End Sub

    Function AddCSV(ByVal Item As String) As Boolean
        Dim arrFile() As String
        Dim FileReader As StreamReader
        Dim Readline As String = String.Empty
        Dim arrReadline() As String
        Dim oLocation As New Locations
        Dim UserLocation As String
        Dim GroupLocation As String
        Dim ErrorArraylist As New ArrayList
        Dim ErrLocation As Boolean = False
        Dim Results As String
        Dim i As Integer
        Try
            arrFile = Item.Split(CChar("\"))
            If sLogFilename.Length = 0 Then
                sLogFilename = arrFile(UBound(arrFile))
            Else
                sLogFilename = sLogFilename & " - " & arrFile(UBound(arrFile))
            End If
            sLogFilename = sLogFilename.Replace(".csv", "")
            FileReader = New StreamReader(Item)
            Do
                Readline = FileReader.ReadLine
                If Not (Readline Is Nothing) Then
                    lstUsers.Items.Add(Readline)
                    arrReadline = Readline.ToUpper.Split(CChar(","))
                    UserLocation = oLocation.SetUserLocation(arrReadline(0))
                    GroupLocation = oLocation.SetUserLocation(arrReadline(1))
                    If UserLocation <> GroupLocation Then
                        ErrLocation = True
                        ErrorArraylist.Add(Readline)
                    End If
                End If
            Loop Until (Readline Is Nothing)
            If Not (FileReader Is Nothing) Then
                FileReader.Close()
            End If
            If ErrLocation Then
                Dim fError As New _Error
                fError.Show()
            End If
        Catch ex As Exception
            CreateDebugLog("OpenDialog" & vbCrLf & ex.ToString & vbCrLf & "----------------------------" & vbCrLf)
        End Try
    End FunctionStart Free Trial