[SOLVED] Laptop screen shows red/black grid of dots ?

[kappa_800]

Hello

I'm using Lenovo Z50-70 (Core i3 4th gen, with Nvidia/Intel hybrid graphics.
I've three problems:

1. Three white horizontal line appeared one day.
2. Screen gets these black/red grid of dots all over the screen. These dots always appear when I increase the brightness. If the brightness is at the lowest they never appear.
3. The screen doesn't refresh accurately, old and new frames in a video overlaps.

See these images and video.
Image 1
Image 2
Image 3

Edit: video overlap is called 'ghosting'.
Edit 2: Output on an external monitor connected through vga port is just fine.

 

[hang-the-9]

Did you install the video drivers and chipset drivers from Lenovo support site?
Usually screen glitches like this are either driver issues or failed video hardware. If you swap between the video cards does the image clear up?
I'm guessing either the nvidia or the onboard video is bad. Try different RAM also, Intel graphics would use system RAM and faulty RAM can cause video glitches.