HP probook screen fault many times

[Andi Ondrejka]

hi
I have the HP probook 4730 with I5 processor and swichable VGA, one is a Intel HD 3000 graphics, and second is Ati Radeon HD 7400M

it work properly almost times, but always, when i work longer time it get fault. its not depend if i work with graphics hard, or just keep laptop starded without any work, it can hapen after one hour, or also after 5 hours,
, just work normally and in moment i can see on screen only lot of lines and broken pictures.
after i must stop laptop hard by On/OFF button, and when i start it again, it work again normally
what i can be?
i have all drivers installed properly, i really do not have idea what is it about

 

[Andi Ondrejka]

https/www.facebook.com/photo.php?fbid=742412982457535&set=a.742412929124207.1073741840.100000665200129&type=3&theater
it look like this
really always it look little different, but always same kind of fault