1. Start by creating your presentation. Be sure to add automatic timing so that the presentation advances by itself. Write down its complete location; for example, c:\articles & presentations\intro.ppt.
2. Check that the date and time on your computer are accurate. You can find it in the system tray. Double-clcik the time to change it. (If you don't see the time, right-click the Start button and choose Properties. Then click the Taskbar tab and check the Show the Clock check box.)
3. Open the Scheduled Tasks folder by choosing Start > All Programs > Accessories > System Tools > Scheduled Tasks.
4. Double-click the Add Scheduled Task item to open the Scheduled Task Wizard and click Next.
5. In the next window, you can choose a program from the list. Interestingly, PowerPoint wasn't on my list. (Neither was Word or Excel, but Outlook was.) In this situation, you want to find the PowerPoint executable file, so click the Browse button. (Note: You can also choose a presentation file, but it will open in Normal view, not Slide Show view. You might think that you could point to a PPS file, but unfortunately, this doesn't work -- it still opens in Normal view!)

6. Browse to your PowerPoint executable file. It's called powerpnt.exe. Mine was in c:\Program Files\Microsoft Office\Office 11, but your path may be different. Click Open.
7. Your wizard now lists POWERPNT as the task name. Since you want to play a particular presentation, change the name to something more meaningful and choose the One Time Only option, unless you want to run the presentation every day, week, or month. Click Next.

8. On the next screen, enter the start time and date. (You can use the the arrows and the pop-up calendar.) Click Next.
9. On the next screen, you enter the login name and password. If you're the only one using your computer, leave the password blank but make sure to note the instruction pertaining to this situation in Step 12. Click Next.
10. On the next screen, make sure to check the Open Advanced Properties for This Task When I Click Finish check box. You still have several adjustments to make! Then click Finish.
11. You now see the Properties of the scheduled task. (You can access this at any time by going to the Scheduled Tasks folder and double-clicking the task.) You need to change the command line switch to tell PowerPoint to open the specific presentation you want and to open it in Slide Show view. To do this, you add the following after the existing command in the Run text box.
/s "c:\articles & presentations\intro.ppt"
Of course, the location and name of your presentation will be different. In my case, the entire command read as follows:
"C:\Program Files\Microsoft Office\OFFICE11\POWERPNT.EXE" /s "c:\articles & presentations\intro.ppt"
(Note: The original command is enclosed in quotes. The /s must be outside the quotes. Your path should be in quotes.For a complete list of command line switches, see Steve Rindsberg's Command Line Switches - PowerPoint and PowerPoint Viewers page.)
12. Check the Run Only If Logged On check box. You must check this box to run the presentaton if you didn't include a password. Then the task will run as long as you're logged on to your computer.
If you just want to play the presentation once, you're done. If you want to repeat it, there are a couple more steps.
13. Click the Schedule tab where you can finalize or change the schedule. For more options, click the Advanced button where you can repeat the task every x minutes or hours until a specific time or for a specific duration. For example, to run the presentation at 11:00 am and 2:00 pm, you could set it to start at 11 and repeat it every 3 hours until 2:30 pm, assuming that the presentation runs for 1/2 hour. Click OK to close the Advanced Schedule Options dialog box. If you want to repeat the presentation continuously, time it and set the time in the Every text box to a little longer than the length of the presentation. Here you see a setting that repeats the presentation every 10 minutes for an hour.

14. Check the If the Task Is Still Running, Stop It at This Time check box. If you don't check this text box, the black "End of Slide Show, Click to Exit" screen remains at the end of all the repetitions.
15. There's still a problem. When the presentation completes one run-through that black "End of Slide Show, Click to Exit" screen remains. This interferes with the next run-through. If you click or press Esc right after a run-through, the task will repeat properly. But if you won't be there to do that, you need to do one more step. Click the Settings tab.
16. In the Scheduled Task Completed section, check the Stop the Task If It Runs for check box and enter a time that is longer than the length of the presentation but shorter than the repetition time. For example, if the presentation is 8 minutes long and you're repeating it every 10 minutes, set the task to stop every 9 minutes. If, as in our original example, you're repeating a presentation every 3 hours, and it runs for 1/2 hour. set the task to stop after 31 minutes.
You're done!
Now your presentation will start on schedule in Slide Show mode, repeat as you specified, and end when you specified.
What if you don't want the desktop to show between repetitions?
You might try a second presentation with one slide that says "Introductory Presentation at 11:00 am and 3:00 pm" and try setting the timings so that it displays the rest of the time. You'll have to be very precise in your settings.
If you're having trouble getting this to work, try creating two separate tasks that start the presentation at the two times. But be sure to stop each task on the Settings tab.
This is a complex process, but it can work well. I suggest that you start, as I did, with a 4 second presentation and set it to repeat every 2 minutes 3 times, stopping the task after 1 minute. That way you won't waste too much time getting it to work. Once you have the technique down, you'll find it easier to start and repeat longer presentations automatically.