Windows Vista forum: Vaio VGN-CS36MJ Abnormal shutting down behavior..!!

Hi everyone,My vaio(intel centrino 2.53 Ghz) is really really troubling me a lot.After startup,everything runs fine till about 2-3 mins,when everything fails,screen goes black,hard disk light goes off,speakers die,usb ports shut off,if external display is connected beforehand,it shows no-signal message at this point.Power light and (battery charging light if charger is connected) stay on,fan runs normally as before and it never recovers from this state until i restart it forcefully,after which the same happens.In one of the many desperate attempts i used recovery disks to make it factory fresh and abnormally during this long process.the laptop didn't die.However after starting windows,it was the same old story.I also ran vaio-care hardware-diagnostic and it showed that the hardware was okay.Just for information,I didn't drop my laptop or spilled anything on it.Finally i took to a vaio approved service center and after charging me,they said that the gpu had failed and that the motherboard needs to be replaced.Unsurprisingly,the cost of the motherboard was few short of a new better sandy-bridge laptop.Interestingly,its 1.5 years old and still under 3 years vaio official warranty but neither is sony online support helping me nor is their service centers.The thought of the quality of the product(toshiba hard drive&LG lcd) and the money i spent on it and the quality of service makes me infuriated.As for the past 3-4 months its completely useless.Any Advice would be appreciated....Thanks..