Reair required on Sony Vaio

Question

Hi,I have a laptop as above,( sony vaio VGN-S1HP )the problem is as follows.When switched on power lights come on but at least 70% of the time the screen remains “Blank” and hangs and will not boot…..sometimes after a while if you switch it of and back on again it will then Power up,and everything fine?....do you know what causes this ? and can you fix it? And obviously a costing….I believe this is apparently a common fault with these. Regards Tom.