iPhone 3g hardware problem

I have a problem with my iphone 3g, i tryed to charge it to PC and after i have pluged in the data cable it suddently stoped ( he shutdown) and he was doing nothing ( black screen), even if i press the power button he doesnt start. After i unplug it and plug into the wall charger, when i press the power button he started up , the apple logo appears and suddenly he is off again . Which is the problem ? Could it be repaired in Romania at Orange Shop ? What should i do with it to make it work again.
P4 Windows XP