Is this behavior irrespective of power condition of the laptop, ie both ac and battery?
Please see bios bulletins for your system here.
Sometimes a bios update can correct this kind of problem...
However, also note this article.
In the probable event that none of that works, it's probably your inverter or backlight (EL) panel, both of which can be replaced. The white lines are not a good sign. See other thread discussions of same here
Google "diagnose laptop monitor failure" for more, or see this repair guide.
I hope this information allows you to resolve this issue. If you need further assistance, please post back with a comment to this thread.
If I've managed to answer your question or solve a problem, please take just a moment to rate this post....thanks!