I have an HP laptop about 3 years old. It freezes at various intervals - sometimes when booting up, sometimes in the middle of doing something. The screen either goes black or it just freezes - NO ERROR MESSAGE.

Ctrl, Alt Del does nothing - it responds only to a fresh reboot.

I have done:
Cleaned with CC cleaner
Done a check with malware bytes
Disabled everything in boot except my anti virus checker
Cleaned temp files, cookies etc on chrome
Done an extensive HARDWARE check using the authrorised HP software
Checked the temp of the CPU using software - it seems to be ok. 35c
Done a virus scan check using avast
Disabled Defender virus checker.

As I get no error message I cannot be more specific. It started a week or so ago. My laptop has been flickering for a while (seems to have stopped now) so I checked all my drivers that I could think of for updates especially the display drivers. I'm out of ideas.