Cross Threading Errors

Imports System.IO
Imports System.Threading
Public Class Form1
    Public tInterval As Integer
    Public Writer As Thread
    Public func As Thread = New Thread(AddressOf processStarter)
    Public read As Thread = New Thread(AddressOf fileReader)
    Public a As Integer
    Public p As Process = New Process
    Public reader As String
    Public Function fileWriter()
        Dim wri As StreamWriter
        wri = File.CreateText(Application.StartupPath + "\fix.bat")
        wri.WriteLine("@echo off")
        wri.WriteLine("cls")
        wri.WriteLine("echo HELLO WORLD")
        wri.WriteLine("echo pause")
        wri.WriteLine("pause")
        wri.Close()
        a = 1
        Return a
    End Function
    Public Function processStarter()
        p.StartInfo.FileName = Application.StartupPath + "\fix.bat"
        p.StartInfo.Arguments = ""
        p.StartInfo.UseShellExecute = False
        p.StartInfo.RedirectStandardOutput = True
        p.StartInfo.Verb = "runas"
        p.StartInfo.WindowStyle = ProcessWindowStyle.Maximized
        p.Start()
        read.Start()
        Return 0
    End Function

    Public Function fileReader()
        Try
            MsgBox("I HAVE OPENED")
            reader = p.StandardOutput.ReadToEnd
            RichTextBox1.Text = reader
        Catch ex As Exception
            MsgBox(ex.Message)
        End Try
        Return 0
    End Function
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Timer1.Enabled = True
        Timer1.Start()
        Button1.Text = "Please Wait.."
        Button1.Enabled = False
    End Sub
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        tInterval = 0
        a = 0
    End Sub
    Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick
        tInterval = tInterval + 1
        Label1.Text = Str(tInterval)
    End Sub
    Private Sub Label1_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Label1.TextChanged
        If tInterval = 1 Then
            Writer = New Thread(AddressOf fileWriter)
            Writer.Start()
        End If
        If tInterval = 2 Then
            Timer1.Stop()
            Writer.Abort()
            func.Start()
        End If
    End Sub
End Class