I am trying to put together a PC that will be used by an autistic boy. As part of his education he is given access to a computer for specified periods of time. I would like to find a hardware solution that would allow the computer to stay at the logon screen until something physical, like a usb key or smart card is inserted somewhere in the system. The idea is to let the boy have a physical object associated with the time he is allowed to use the computer. Something coin based, would be ideal, but I have never seen hardware for that purpose. I have seen various USB key systems that might do this, I am wondering if anyone has experience with something like this and can recommend a product.
I am also looking for a software solution that will auto logout after a specified period of time.
All help or advice will be greatly appreciated.