HP Pavilion go keeps crashing

For a while my HP Pavilion GP keeps crashing. Sometimes it goes to a black screen or sometimes it goes to a static grey screen. Either way once that happens the laptop does not come on again until I wait a week or so and then it comes on for a few hours and the same thing happens again. I have tried taking the battery out and pressing power. Does the laptop need an internal clean, replacement part or has my laptop come to the end of its' use even though I've only had it for 18 months. Any advice would be useful. Deesh