Horizontal lines on laptop

[Hicsousi]

When i boot up my probook 6550b I see this:

But when i connect it to a monitor, the picture on the monitor is normal but the laptop display stays the same. After maybe 10-15 minutes the laptop display fixes itself. I searched for solutions online, but everyone suggests that the screen is broken, but that is not the case with my laptop.

 

[jarotech]

Hi, try reinstalling the connector on the back of the screen, if you have the same problem, then, probably the screen is defective.