Actually, I'm a mother and I stand behind what I originally said which
you misinterpreted: I can't imagine what files a 5-year old child would
be reading and/or having the opportunity to delete on a shared
computer. A 5-year old child should not be on a computer unsupervised.
In case you didn't understand what I meant, here it is again:
If he's old enough to use the computer, he's old enough to learn
the word, "No". If you let a 5-year old child delete files on a shared
computer, then you deserve what you get.
Many people don't have two computers or know enough to setup permissions
or even use NTFS.
If the person in question had know to use NTFS, create an account for
the adults and one for the kids, then used NTFS security permissions to
protect the shared folders they store their documents in, as long as the
kids were just "users" they would not be able to delete any secured
files/folders.
As a father of three kids that started using computers at age 3, it was
simple for me to setup areas where they could interact with the system
(s) and still secure my data - but being a network admin I already knew
how to secure it. Most home users don't have a clue about NTFS or
security settings.
Rather than preach to them about monitoring kids, which could still lead
to deleted files, how about explaining to them the merits of file/folder
security.