Slow, screen flashing black upon playing videos, Chrome won't open

[wifi_bsod]

OS: Windows 10
Laptop: HP Pavilion
Problem: Many

This is for my sister's laptop. Her drawing tablet wasn't working correctly and she also wanted to install "Minecraft for Windows 10." Therefore, she updated her Windows 10. Afterwards, everything was very slow - when trying to make a new folder on the desktop, right-click took a half-minute, then placing the cursor over 'new' took even longer. When she played a video on Youtube, everything would flash black, as well.

She ran Avast antivirus and Malwarebytes, but nothing showed up. She did a System Restore, but the problems persist. And now Chrome won't open.

What should I tell her?

[2x3i5x]

Just wondering how the computer performs when you boot to safe mode. Generally, safe mode runs only the bare minimum to get windows to run, and none of the other things you may have installed and perhaps it may help in the diagnosis of the issues.


If you needed help getting there, one of these links may help:
https://support.microsoft.com/en-us/help/12376/windows-10-start-your-pc-in-safe-mode
https://www.bleepingcomputer.com/tutorials/how-to-start-windows-10-in-safe-mode-with-networking/

[wifi_bsod]

It boots into safe mode with networking, but no internet. Also, an update on what she means by the youtube thing: the whole screen, minus the Windows taskbar, turns black if a Youtube video is playing but the mouse cursor is not on the video. If the mouse cursor is outside of the playing video, or she lets it idle on the video and it disappears, the screen turns black until she moves the mouse on the video.

[wifi_bsod]

Update: uninstalling and reinstalling fixed Chrome apparently. She says she can watch youtube in miniplayer and theater modes, but not normal or fullscreen. Those still make the whole screen go black.