BSOD upon user log in

[Kaia]

Hi! So recently my mother told me she couldn't use her PC anymore so I checked and she gets the so called Black Screen of Death upon log in. It doesn't even work on safe mode. I tried restoring to the last known good configuration and it worked after trying the different restore points, but only temporarily as the next time she logged in the black screen welcomed her once again - it's like that everytime. Now the restore points have changed and none of them work anymore. When I log in a reminder from Norton pops up on the screen (her anti-virus has expired) and when I click the button for online support the default browser, Google Chrome, opens up and I'm able to surf the Internet just fine. Also, maybe it's not related but I noticed that the volume adjustment keys on the keyboard have stopped working. When I press the Windows key, Start menu doesn't show either. If someone could tell me how I can proceed onto Step 3 (running System Health Report via Start when I can't access it) I'd appreciate it as I'm not so good at these things sorry! Thanks.