Is there a way that Windows 7 can remind me (with a dialog box for example) to complete some particular tasks before shutting down, such as locking my secret files and logging out from some services?
If you have logon auditing enabled (which you can do from the Security Policies management console,
If you were to use a logoff script, you would want to create the script, most likely using VBscript, and then use group policy settings (
This is just an example, which shows a warning-style box with a single OK button. For full documentation, see the MSDN article on MsgBox.
...which gives you
Go to Windows Task Scheduler, and create a task. In the Triggers section, click New... and in the Begin a Task... drop-down, select the option that works best for you.
There a lot of different options etc. to choose from. Enjoy!