My computer freezes every time I get up and go into another room,?

Even if I only leave for only 30 seconds or so The *!*! thing is
frozen when I get back I end up having to hit the reboot button and start over.Sometimes when I put my computer on standby and try to start a new session the next day I find that it is frozen and have to reboot! help!!!!!!

P.S. I checked all the connections (even on the inside).

signed,
mike