想要调用系统屏幕保护，主要是发送一个WM_SYSCOMMAND消息即可。
Private Declare Function SendMessage Lib "user32" Alias "SendMessageA" (ByVal hwnd As Int32, ByVal wMsg As Int32, ByVal wParam
As Int32, ByVal lParam As Int32) As Int32
Private Const HWND_BROADCAST = &HFFFF&
Private Const WM_SYSCOMMAND = &H112
Private Const SC_SCREENSAVE = &HF140&
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
SendMessage(HWND_BROADCAST, WM_SYSCOMMAND, SC_SCREENSAVE, 0)
End Sub
