The program known as variously as Antivir, Antivir 2010 and Antivir Antivirus. It is a rogue anti-malware program. There are many, many of these things.
Typically, they start with a pop-up while you're on the Internet. They offer a free scan. Assuming you bite, they announce you have Trojans and viruses on your computer. Send us money, they say, and we'll clean your computer.
Of course, none of this is true. Let's say you actually bought this software. After you ran it, you might want to rerun the original scan. It would "find" the same things.
These programs are technically adware. They get on your computer and demand that you buy. They are known on the street as fraudware or scumware.
There is an additional aspect to Antivir. It is easily confused with Avira AntiVir, a legitimate product. As a matter of fact, I recommend Avira. I doubt that the name duplication is coincidental.
Unaware, You probably clicked a pop-up. After all, what can a free scan hurt? But in so doing, you allowed this thing to install on your computer. (Fraudware could also be installed via an e-mail attachment. Or, it could have been a drive-by download. These take advantage of unpatched holes in Windows. But pop-ups are most common.)
STOPzilla is an anti-spyware program. That's why the pop-ups stopped. Why did it take 12 hours? I'm not sure. Some of the people who develop malware programs are good. That thing probably burrowed into Windows.
I suppose somebody somewhere would take a report. It would be filed under "Things to Ponder on a Rainy Day." In other words, it would be a waste of time.
Most likely, the people behind this are criminals. And they're probably located overseas. Finding them would be next to impossible. And prosecuting them successfully? Don't hold your breath.
Free antivirus software: