Be careful. It could be to mislead you and steal your password.
Next time it happens make a screenshot and show it to someone with computer skills before you do something, if you don't know what to do.
(Press the print screen button on your keyboard, then start "Microsoft Paint", then click "paste", then save the file).
These days if you don't pay for an antivirus pack,
there are sometimes features missing that are needed (like a firewall for example).
So using a free anti-virus is an increased risk.
Not all anti-virus software is the same either.
I tested 39, and could find none without security risks,
even "the best" have flaws. Not sure why, it doesn't seem hard to fix certain problems.
It almost seems deliberate.
It's also about updates.
Using an old Windows that can't be updated or not updating your windows is of coarse no good,
not regularly updating your browser and all software that connects to the internet,
and not updating your modem/router firmware, is all risky.
But as they say: the weakest link remains the person using the computer.
I use gentoo linux and artix linux where I don't worry about malwares.
Linux + Brave web browser + dnscrypt-proxy( encrypts your DNS traffic) + tor browser + nftables firewall = increased privacy and security
Anti-virus programs are surveillance programs. Why do you think Bill Gates made windows vulnerable to viruses?
The goal was to make you depend on anti-virus programs which are surveillance programs.
Windows makes you depend on anti-virus(vaccine) programs.
Bill Gates is also busy scaring people with coronavirus.
Bill Gates sells vaccines for computer viruses and biological viruses.
By the way, it's very likely that biological viruses don't really exist.
Exosome theory makes more sense than virus theory.
Do you know that Bill Gates wants to inject vaccines with self-replicating surveillance nanobots into your bloodstream in the near future?
You don't want surveillance programs. Come to linux or apple mac os or BSD.
Artix Linux is the best linux distribution that I know.
Artix Linux + i3 window manager + picom compositor = security and beauty