You cannot make the horse drink but you can teach him how to drink.

My point is while you are at the customer's premise to fix their machine, you need to give some tips on how to browse safely the internet and most importantly set up their machine with a limited user account rather than the admin account. I have seen time and time again people using their computer with all admin privileges.

It's a never ending problem and will continue to be so until end users are well educated and aware of the dangers of the internet if they are careless.

If users don't know the dangers of browsing carelessly, then it's our moral and professional duty to show them and educate them.