Здравствуйте, rtbsd
Попробовал поставить ваш код, но ошибка всё та же. вот полный код проги:

Imports System.IO
Imports System
Imports System.Runtime.InteropServices
Imports System.Windows.Forms

Public Class Form1
    <DllImport("KERNEL32.DLL", EntryPoint:="MoveFileW", SetLastError:=True, _
CharSet:=CharSet.Unicode, ExactSpelling:=True, _
CallingConvention:=CallingConvention.StdCall)> _
    Public Shared Function _
    MoveFile(ByVal src As String, ByVal dst As String) As Boolean
        ' This function copies a file from the path src to the path dst.
        ' Leave function empty - DLLImport attribute forces calls 
        ' to MoveFile to be forwarded to MoveFileW in KERNEL32.DLL.
    End Function

    Private Declare Function FindWindow _
        Lib "user32.dll" Alias "FindWindowA" ( _
        ByVal lpClassName As String, _
        ByVal lpWindowName As String) As Long
    Private Declare Function ShowWindow _
            Lib "user32.dll" ( _
            ByVal hWnd As Long, _
            ByVal nCmdShow As Long) As Long

    Private Sub HiddenTaskBar()
        ShowWindow(FindWindow("Shell_TrayWnd", vbNullString), 0&)
    End Sub

    Private Sub VisibleTaskBar()
        ShowWindow(FindWindow("Shell_TrayWnd", vbNullString), 4&)
    End Sub

    Private Sub Form1_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load
        HiddenTaskBar()
    End Sub
End Class