Auto update issue with drive C:/ in Vb.net - vb.net

Question

I've created a program with Vb.net that includes an "auto-update" feature. I made it using File A Sync and it seems to work fine, But that's only when I set up the program in any drive except the "C:/" drive, But when I set up the program on the "C:/" drive, The download doesn't start at all. I do not know why. I also tried searching for this issue online but couldn't find any help.
Imports System.IO
Imports System.ComponentModel
Public Class Updater
Dim client As New WebClient
Private Sub Updater_Load(sender As Object, e As EventArgs) Handles MyBase.Load
Downloading_Bar.EditValue = 0
Speed_lb.Visible = True
Speed_lb.Text = " 0 kb/s"
Size_lb.Visible = True
Size_lb.Text = " 0 MB's / 0 MB's"
Try
AddHandler client.DownloadProgressChanged, AddressOf Client_ProgressChanged
AddHandler client.DownloadFileCompleted, AddressOf Client_DownloadCompleted
client.DownloadFileAsync(New Uri(Program_URL), Application.StartupPath & "\Changer NewVersion.exe")
Downloading_Bar.Properties.Step = 1
Downloading_Bar.Properties.PercentView = True
Downloading_Bar.Properties.Maximum = 100
Downloading_Bar.Properties.Minimum = 0
Catch ex As Exception
DevExpress.XtraEditors.XtraMessageBox.Show(ex.Message, "Error", MessageBoxButtons.OK, MessageBoxIcon.Error)
End Try
End Sub
Private Sub Client_ProgressChanged(ByVal sender As Object, ByVal e As DownloadProgressChangedEventArgs)
Try
Speed_lb.Text = String.Format("{0} kb/s", (e.BytesReceived / 1024.0).ToString("00"))
Downloading_Bar.EditValue = e.ProgressPercentage.ToString()
Downloading_Bar.PerformStep()
Downloading_Bar.Update()
Size_lb.Text = String.Format("{0} MB's / {1} MB's", (e.BytesReceived / 1024.0 / 1024.0).ToString("0.00"), (e.TotalBytesToReceive / 1024.0 / 1024.0).ToString("0.00"))
Catch ex As Exception
DevExpress.XtraEditors.XtraMessageBox.Show(ex.Message, "Error", MessageBoxButtons.OK, MessageBoxIcon.Error)
client.CancelAsync()
client.Dispose()
End Try
End Sub
Private Sub Client_DownloadCompleted(ByVal sender As Object, ByVal e As System.ComponentModel.AsyncCompletedEventArgs)
If Downloading_Bar.EditValue = 100 Then
Try
My.Computer.FileSystem.RenameFile(Application.StartupPath & "\Changer.exe", "Changer OlderVersion.exe")
My.Computer.FileSystem.RenameFile(Application.StartupPath & "\Changer NewVersion.exe", "Changer.exe")
Process.Start(Application.ExecutablePath)
Process.GetCurrentProcess.Kill()
Me.Dispose()
Catch ex As Exception
DevExpress.XtraEditors.XtraMessageBox.Show(ex.Message, "Error", MessageBoxButtons.OK, MessageBoxIcon.Error)
End Try
End If
End Sub
Private Sub Updater_FormClosing(sender As Object, e As FormClosingEventArgs) Handles Me.FormClosing
client.CancelAsync()
client.Dispose()
End Sub
End Class