PC Boots fine after full shutdown but gets "boot device not found" after any restart

[CMermaid]

Whenever my PC restarts (say from a Windows update, or any time I click the Windows logo>power>restart), I see the Boot Device Not Found - Hard Disk (3F0) error and the PC will not boot. But if I then power off the PC with the power button, and then turn it on after a few minutes, it boots completely fine.

The hard drive is a Samsung 256GB SSD drive.

Any tips on how to fix this? What I've tried:

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When I get the boot device error, if I press F2 to and do the hard drive quick test, it says it can't find the hard drive. However, if I then shut down and start up the computer using the power button, it boots fine (so it obviously can find the hard drive and the hard drive works fine).

The HP diagnostics also say the hard drive is fine.

When I'm having the Boot Device Not Found issue, I've also pressed F10 to get into the BIOS setup. The date and time is fine. I've reset the Bios, and I've also checked the Boot options and it's not set to Legacy (it is set to UEFI).

I have also completely reinstalled Windows and chose the reinstall option that removes my files and apps. So I now have a clean PC with pretty much only Windows on it.

But, if I click Windows > Restart...I see Boot Device Not Found. If I then press the power button, leave the PC off, and press the power button again in a minute or so, the PC boots perfectly and works fine.

Any other ideas on how to fix this??

[CMermaid · Accepted solution]

I solved the problem!  Even when I reset Windows, HP was installing a trial version of Avast VPN software on my PC. I uninstalled the Avast software and the problem went away.