Desktop doesn't boot

[Fulvio73]

Hi, 

My brand new pc, after the first start up and configuration (a couple hours of correct working), showed me a pop-up in the bottom right part of the screen asking to restart to complete a security update. I agreed, the machine restarted but a few seconds into the boot procedure and I got back a noisy beep, the screen turned white requiring some kind of password (with a drop down menu asking me to select the language).

Of course no password works. It's also impossible to enter the bios (I tried to restart pushing every Function button on the keyboard but no bios)...it always ends up in that noisy beep and the white page asking the **bleep** password. Can someone help me, please?

 

[Fulvio73]

After one hour on the phone with a guy called Petar (from Serbia), the problem seems to be impossible to solve.
The guy told me that I have to pay for assistance. Well, for a machine bought a week ago, shipped yesterday, been on for a couple hours and finally stuck to an unknown page (asking me an unknown password) after a restart needed by a HP security software runnig an unrequested update. 

ARE YOU KIDDING ME?