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I have a PC at home running on Windows 7, 32-bit.
Recently, when clearing the temp folder (accessible by pressing %temp% on the Run command), I found that the folder has got some foul videos downloaded from Internet. By foul, I mean totally disgusting, of a very, very, very low level (like pornographic, horrible scenes, etc. which I can't mention). This has been occurring quite often. They come after some days even if I delete them.
I have a licensed copy of QuickHeal in my computer, and a full system scan at great depths shows that there is no virus, malware or any other system change. Behaviour Detection is set to highest security. Firewall is also on.
Our computer is accessed only by my father and me. We never visit any foul site, not even Facebook or Twitter or Google Plus. My father visits a travel forum, while I mostly use it for Java programming.
Moreover, the computer has recently started to crash frequently. We've called a mechanic, who could find no error. The computer has got 4GB RAM, yet sometimes everything on the screen freezes and then everything crashes, including Windows. The task bar and start button are not accessible, and mostly we have to power off the computer and reboot it.
The files come only if connected to Internet. We've tested, and not connected the PC to Internet for a month, and no videos had come.
We work on either Opera browser or Chrome. Both these browsers are known for protecting users from malicious sites. We've installed anti-tracking extensions to browsers like Ghostery to prevent tracking.
So, why are these videos coming? I feel somebody is bypassing QuickHeal security firewall and accessing the computer. I conduct a full system scan and a backup every week, so I'm not greatly worried for files, but what is it? What can I do to prevent this? How can I know who is accessing the computer by hacking firewall?
N.B.: somebody wanted to mark this as a duplicate to this one. Let me explain the difference. I don't even know till now whether the computer has been hacked or its a virus. Until and unless I'm confirmed it's a virus, it's not a duplicate.