Inspiron 1420-no display

Hi everybody,

Actually the problem started 1 month ago. During that time, I could not restart my laptop. When i switched on properly, it showed no display while my cpu is working and i could hear the window opening. So, i let it rest for few hours and tried to open it again. This time it showed display. However, it last only few hours then it shut down by itself again. So, I sent my laptop to the shop and they reformat my laptop and everything was fine after reformating except that the driver for nVidia Geforce 8400 graphic card could not be installed.

Recently, the problem recurs. No display during startingm off the laptop while the cpu is running. So, what is the problem?Is it the screen problem or might be any other problem?

Thank you!!