dkc,

I do not want to disappoint you but your approach is very unsafe. I have been
through the same request and ended up nowhere with Excel:

1. As you are using a file, a smart user can go and delete this file
2. If I am not mistaken, you cannot share a file with a password, then your
file will be editable by any user. And hiding a file, even deep in a folder
structure is not very secure (Try search files modified today)

A better way is to use a database like SQL Windows or Oracle. Ask your
database administrator to create a table where everyone can add records, but
not modify nor delete. Then, connect to the database with your macro and
write the record.

In Powerpoint, you must also ensu
1. Your code is protected by a password
2. The user cannot go directly to the last slide of the presentation (do you
know that renaming a file from pps to ppt makes it editable in Powerpoint),
then go to slide view and click the button. To overcome that, I added on each
slide a variable and tested at the end that all these variables add the value
"read"
3. You should prevent users to keep the down arrow pressed, so all the slides
are viewed at light speed, without being read. I installed a timer on each
slide, blocked navigation and displayed "Previous" and "Next" buttons once
the timer was over. I did this for each slide, with a different time.

Good luck,
Stephane.