Download the Shutdown Stopper freeware.

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"Shutdown Stopper v2.1
Copyright 2000-2001 Outside The Box Software (http://kickme.to/otbsoft)
Coded by Douglas Good
Released as Freeware June 24, 2001

Shutdown Stopper is a simple program that prevents your computer from shutting down and rebooting. I wrote this after running an installation program that tried to force me to shut down and reboot. Most times, install programs ask you whether you want to shutdown right away, or wait until later. This one (which happened to be Norton Anti-Virus's Live Update) didn't give me an option - it was going to force me to shut down, and I didn't have a choice. Unacceptable. Shutdown Stopper was born.

To use, just run the program, and it will stop your PC from shutting down. It works because Windows sends a shutdown request to each running application before it actually shuts down. If the application says OK, it will be terminated. Once all the apps are terminated, Windows will shut down the PC. Shutdown Stopper just says "NO" to the shutdown request, and Windows will then abort the shutdown process. There is a way programs can force a shutdown that will override Shutdown Stopper, but most properly-coded software won't do this. In fact, even selecting Shutdown from the Windows Start menu won't work if Shutdown Stopper is running.

Shutdown Stopper runs in the Windows Notification Tray on your Start Menu bar. When you run the program, it will put a red, stop-sign shaped icon in the tray, and shutdowns will be disabled. You can either right-click on the Icon to bring up a menu with options, or you can left-click and open the main program window. Either way lets you enable or disable shutdowns, exit the program, or turn off shutdown notifications so you won't be told when a shutdown attempt has occurred. Other options, such as running a command when a shutdown attempt occurs are only available from the main window's Setup tab.

You may optionally execute a command when a shutdown attempt is encountered. On the SETUP tab is a checkbox labeled "Issue shutdown attempt commands". If this checkbox is checked, ShutStop will try to issue the command in the memo box on the line that corresponds to the shutdown attempt number. In other words, on the first shutdown attempt, the command on the first line of the memo is executed. On the second attempt, the command on the second line of the memo box is executed, and so on. If the "Use first for all" box is checked, the command on the first line of the memo will be used every time a shutdown attempts occurs. This prevents you from having to enter a bunch of identical commands when you want the same command issued on every shutdown attempt. The commands listed in the memo box should include the full path and filenames of an executable or batch file to run, as well as any command line parameters. The browse button will add whatever path and filename you select into the memo box, on a new line. The Save button saves the settings, and they'll be automatically loaded the next time ShutStop is run.

NOTE ABOUT RUNNING COMMANDS ON SHUTDOWN: If you have ShutStop set to deny shutdowns, you should have no problems with issuing shutdown attempt commands. However, if you are allowing shutdowns, the operating systems may not allow ShutStop to execute another program, because Windows is shutting down. I believe the Windows 9x operating systems allows the command to be executed, but NT and 2000 probably don't. This is a feature of the operating system, and cannot be controlled by ShutStop. So if you're denying shutdowns, everything should be fine, but if you're allowing them your commands may not actually be executed. I'll have to test this further as I have the time and opportunity."