Adding keystrokes - Slide show via macro

Hi!

My office computers are all WinXP SP2 under corporate group policies
applied by the technology department. There is a criteria that if the
computer is idle for 5 minutes, it gets locked and you get the windows
logon streen asking you to hit CTRL+ALT+DEL to login.

There is no way we can override this as it is a group policy but one
way accomplish this that I thought of is to send keystrokes so that the
computer will never be idle.

What I want to do is, whenever I move off my computer, I will run a
macro within the powerpoint file. This macro should start a slide show.
This macro will have keystrokes, after 5 seconds, the macro should send
a keystroke that will move the current slide to next slide and the
computer will also be in activity state becuase of which the computer
will never be locked. If it reaches the last slide, it should
automatically go the first slide and be in continuous loop.

Now comes the security issue, anybody can cancel the slideshow and work
on my PC. I don't even want that. This can be resolved only by having a
password. If anybody attempts to touch the keyboard keys or click the
mouse button, the macro should assume that its time to quit the slide
show and ask for a password before quitting.

Is it a big ask? Is this possible? If yes, can anyone guide me?

Thanks
Maxi