HP strange electricity problem

Hello

I have a HP pavilion dv4000. The problem is sometimes when i turn on the computer its stuck at black screen, then i shake the laptops body little bit and it starts working, the HP logo comes on. Same thing happens while i m using the computer, the computer totally freezes then i shake it and hit it lightly and it works. during the freezing no USB works, mouse light is gone for ex.

so far two services couldnt fix it, any idea?

thanks in advance