hey guys....while i am playing a game off of the HD for a while the xbox makes a noise like it just turned off... then freezes a few seconds later. and in some cases, when it does freeze i try to turn the xbox off using the normal power off button and all it does is turn off the power/eject button light and the xbox still runs for a moment and the chip is still on.... then it finally turns off. when i do turn it back on, sometimes it fails to load unleashx. the xbox usually does this after a few hours of gameplay... could it be a heat issue??? i tried the whole clear the cache and clear the x y and z drives but it still happens....