Acer Aspire M7300 *FAULTY* +

Acer Aspire M7300 *FAULTY* Windows Vista 64bit, 2.6Ghz AMD Phenom II, 6GB DDR3, 640GB+ 1TB,DVD Supermulti with Labelflash, DVD ROM, ATI Radeon HD4870 1024MB. Restored to factory settings. Comes with NO screen and No Keyboard/Mouse. There is a slight problem in that after 30mins of turning it on. it will freeze. I not sure whats wrong but i think it might be getting to hot, as it works ok on cooler days and i have taken the side off and it worked ok. If you turn it on wait for desktop to load then restart it, It will work perfect for hours.