VB Program file access NEED ADVICE ASAP.....

Imports System.IO
Public Class Form1
    Private Sub btnScan_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnscan.Click
        btnscan.Enabled = False
        Dim searchForTheseFiles() As String = txtFileList.Text.ToUpper.Split(Environment.NewLine)
        Dim fileList As New List(Of String)(searchForTheseFiles)
        Dim myDir As New DirectoryInfo(cboDriveList.Text)
        For Each foundFile As FileInfo In myDir.GetFiles("*.*", SearchOption.AllDirectories)
            If fileList.Contains(foundFile.Name.ToUpper) Then
                MsgBox("AAAAAHHHHH!!!! VIRUS FOUND!!!")

                textbox1.Text &= Environment.NewLine & foundFile.FullName
                Try
                    foundFile.Delete()
                Catch ex As Exception
                    MsgBox("Couldn't delete infected file!")
                    textbox1.Text &= String.Format("{0}Couldn't delete infected file: {1}", Environment.NewLine, foundFile.FullName)
                End Try
            End If
        Next foundFile
        btnscan.Enabled = True
    End Sub

    Private Function foundFile() As Object
        Throw New NotImplementedException
    End Function

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        cboDriveList.Items.AddRange(System.IO.Directory.GetLogicalDrives)
    End Sub
End Class