程序代码：

Private Declare Function SetProcessShutdownParameters Lib "kernel32" (ByVal dwLevel As Long, ByVal dwFlags As Long) As Long

Private Sub Form_Load()
Call SetProcessShutdownParameters(1279, 0&)  '&H4FF = 1279，即本程序被系统最先通知关闭以便触发Form_QueryUnload事件，这样才能最先发现电脑关机、重启、注销事件
End Sub

Private Sub Form_QueryUnload(Cancel As Integer, UnloadMode As Integer)
If UnloadMode = vbAppWindows Then
Cancel = 1  '该语句能让系统不能顺利关机、重启、注销，这样你才有机会反悔并看到后面的对话框。
MsgBox "检测到你的电脑正在准备关机、重启、注销！"
End If
End Sub