Imports System.Windows.Forms
Imports System.IO
Imports System.Text.RegularExpressions
 
Public Class Form1
    Dim filesystem As Object, ThisDir As Object
    Dim mcheck(0) As CheckBox
    Dim winampargs As String

#Region "Propertys"
    Public Property userSelectedPlayerFilePath() As String
        Get
            Return playertextbox.Text
        End Get
        Set(value As String)
            playertextbox.Text = value
        End Set
    End Property
 
    Public Property userSelectedFolderPath() As String
        Get
            Return foldertextbox.Text
        End Get
        Set(value As String)
            foldertextbox.Text = value
        End Set
    End Property
#End Region

#Region "Load / Close"
 
    Private Sub Form1_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load
        playertextbox.Text = My.Settings.playerpath
        foldertextbox.Text = My.Settings.folderpath
        updatecheckboxes()
    End Sub
 
    Private Sub Form1_FormClosing(sender As Object, e As System.Windows.Forms.FormClosingEventArgs) Handles Me.FormClosing
        Dim mCheckados(0) As Int32
        Dim Cuantos As Int32 = 0
        For i As Int32 = 0 To mcheck.Length - 1
            If mcheck(i).Checked = True Then
                Cuantos += 1
                Array.Resize(mCheckados, Cuantos)
                mCheckados(Cuantos - 1) = i + 1
            End If
        Next
        My.Settings.Valores = mCheckados
        My.Settings.Save()
    End Sub
 
#End Region

#Region "Save & Get settings"
 
    Public Sub GenerarPropiedades()
        Dim CheckedN As String = Nothing
        For i As Int32 = 0 To mcheck.Length - 1
            If mcheck(i).Checked = True Then
                CheckedN &= i + 1
            End If
        Next
        My.Settings.Save()
    End Sub
 
    Private Sub CargarPropiedades()
        'Obtenemos la Lista de Enteros de los índices Checkados
        Dim ListaCheckados As Int32() = My.Settings.Valores
        For i As Int32 = 0 To mcheck.Length - 1
            For Each indiceCheckado As Int32 In ListaCheckados
                mcheck(indiceCheckado - 1).Checked = True
            Next
        Next
    End Sub
 
#End Region

#Region "Draw checkboxes..."
 
    Public Sub updatecheckboxes()
        ' delete the old checkboxes
        Panel1.Controls.Clear()
        ' create the new checkboxes
        Dim filesystem = CreateObject("Scripting.FileSystemObject")
        Dim ThisDir = filesystem.GetFolder(My.Settings.folderpath)
        Dim i As Int32 = 0
        For Each folder In ThisDir.Subfolders
            Array.Resize(mcheck, i + 1)
            mcheck(i) = New CheckBox
            With mcheck(i)
                .AutoSize = True
                .Location = New Point(10, i * 20)
                .Name = "CheckBox" & i + 1
                .Text = folder.Name
            End With
            Me.Panel1.Controls.Add(mcheck(i))
            AddHandler mcheck(i).CheckedChanged, AddressOf LlamadaCheckBox
            i += 1
        Next
        CargarPropiedades()
    End Sub
 
    ' función que se ejecuta cuando cualquier checkbox es clickado
    Public Sub LlamadaCheckBox(ByVal sender As Object, ByVal e As System.EventArgs)
        Dim filesystem = CreateObject("Scripting.FileSystemObject")
        Dim ThisDir = filesystem.GetFolder(My.Settings.folderpath)
        Dim CheckboxN As CheckBox = CType(sender, CheckBox)
        If CheckboxN.Checked = True Then
            winampargs = winampargs & " " & ControlChars.Quote & Path.Combine(ThisDir.Path, CheckboxN.Text.ToString()) & ControlChars.Quote
        Else
            winampargs = Replace(winampargs, ControlChars.Quote & Path.Combine(ThisDir.Path, CheckboxN.Text.ToString()) & ControlChars.Quote, "")
        End If
    End Sub
 
#End Region

#Region "buttons"
 
    ' Folder button
    Public Sub C1Button3_Click(sender As Object, e As EventArgs) Handles folderbutton.Click
        Dim folderselected As New System.Windows.Forms.FolderBrowserDialog
        Dim Resultado As DialogResult
        folderselected.RootFolder = Environment.SpecialFolder.Desktop
        Resultado = folderselected.ShowDialog
        If Resultado.ToString() = "OK" Then
            userSelectedFolderPath = folderselected.SelectedPath
            My.Settings.folderpath = folderselected.SelectedPath
            My.Settings.Save()
            Dim mcheck(0) As CheckBox
            updatecheckboxes()
        End If
    End Sub
 
    ' Player button
    Public Sub C1Button1_Click(sender As Object, e As EventArgs) Handles playerbutton.Click
        Dim playerselected As New OpenFileDialog()
        playerselected.InitialDirectory = Environ("programfiles")
        playerselected.Title = "Select your favorite music player"
        playerselected.Filter = "Music players|mpc.exe;mpc-hc.exe;mpc-hc64.exe;umplayer.exe;vlc.exe;winamp.exe;wmp.exe"
        PlayerDialog.FilterIndex = 1
        Dim selection As System.Windows.Forms.DialogResult = playerselected.ShowDialog()
        If selection = DialogResult.OK Then
            userSelectedPlayerFilePath = playerselected.FileName
            My.Settings.playerpath = playerselected.FileName
            My.Settings.Save()
        End If
    End Sub
 
    ' Play button
    Public Sub C1Button2_Click(sender As Object, e As EventArgs) Handles C1Button2.Click
        Process.Start(userSelectedPlayerFilePath, winampargs)
    End Sub
 
#End Region

End Class

Dim ListaCheckados As Int32() = My.Settings.Valores

My.Settings.Valores = mCheckados

        <Global.System.Configuration.UserScopedSettingAttribute(), _
         Global.System.Diagnostics.DebuggerNonUserCodeAttribute(), _
         Global.System.Configuration.DefaultSettingValueAttribute("0")> _
        Public Property Valores() As Int32()
            Get
                Return CType(Me("Valores"), Int32())
            End Get
            Set(value As Int32())
                Me("Valores") = value
            End Set
        End Property
    End Class
End Namespace

Index was outside the bounds of the array. 

    Private Sub CargarPropiedades()
                mcheck(indiceCheckado - 1).Checked = True
    End Sub

    ' Folder button
    Public Sub C1Button3_Click(sender As Object, e As EventArgs) Handles folderbutton.Click
     ...
        If Resultado.ToString() = "OK" Then
            Dim mcheck(0) As CheckBox
            updatecheckboxes()

    ' update checkboxes
    Public Sub updatecheckboxes()
        ' delete the old checkboxes
        Panel1.Controls.Clear()
        ' create the new checkboxes
        Dim filesystem = CreateObject("Scripting.FileSystemObject")
        Dim ThisDir = filesystem.GetFolder(My.Settings.folderpath)
        Dim i As Int32 = 0
        For Each folder In ThisDir.Subfolders
            'MessageBox.Show("a")
            Array.Resize(mcheck, i + 1)
            mcheck(i) = New CheckBox
            With mcheck(i)
                .Name = "CheckBox" & i + 1
                '.Text = mcheck(i).Name
                .Text = folder.Name
                .Location = New Point(10, i * 20)
            End With
            Me.Panel1.Controls.Add(mcheck(i))
            AddHandler mcheck(i).CheckedChanged, AddressOf LlamadaCheckBox
            i += 1
        Next
        CargarPropiedades()
    End Sub

If CheckboxN.Name[(/^#{Regexp.escape(caracter)}$/)] Then...

Dim reg As New Regex(caracter) 
If reg.Match(CheckboxN.Name) Then