Sony vaio laptop

Hi

I am having trouble with my sony vaio laptop, when i switch it on it looks like its doing everything it should but instead of completing start up it goes to black screen then flashes a blue screen with text but i dont have time to read because its only flashes for a fraction of a second, then it shuts down and starts up again to repeat the action over and over again.

does anyone have any ideas how to solve. many thanks