Environment
Your Xbox 360 requires an open environment where it has at least six inches of space on all sides to properly ventilate while in use. Do not attempt to play the system while it is in an enclosed space, such as a media cabinet or a drawer. The console must expel hot air and will overheat in an isolated environment.
Overuse
Your Xbox 360 uses a high-powered graphics engine when it runs games, and the need for power causes the console to heat up. While the system comes equipped with an internal fan, this only delays overheating. Extensive play (six or more hours) will cause the system to overheat and freeze your game on the television screen.
Lead Solder
Internally, your Xbox 360 binds its RAM, CPU and GPU chips to its motherboard with a lead solder. Constant overheating weakens the lead solder, which weakens the connection between the console's internal components. After so long, your console will freeze up continually because the lead soldering has become so weak that it starts to bend and change in heat.
Power Supply
You may be utilizing a faulty wall outlet. Should the system be frequently freezing up and turning off, take notice of your Power Brick (the large brick that plugs into the electrical wall outlet). If the light is red or not lit, the wall outlet is short-circuiting and needs to be replaced.
Red Rings
Red lights will flash on the Xbox 360's Ring of Light in place of the green lights when the system freezes and shuts down. This signifies that the Xbox 360 has experienced a critical hardware error. Basically, the system has overheated and the lead soldering has weakened to such a point that you can no longer operate your console.