Ever had some computer malware spit a bunch of porn onto your screen?

Now imagine it happening in a roomful of schoolchildren.

Now imagine it could send you to jail -- for forty years.

That's what happened to Julie Amero, a substitute teacher in Norwich, Conn., in 2004. Using a computer in a room of seventh-graders -- a computer she'd been instructed not to turn off -- after a couple of the students had gone to a hairstyling website, it suddenly began displaying pornographic images that she couldn't stop.

Prosecutor David Smith contended at her original three-day trial that Amero had actually clicked on the graphic Web sites, according to an Associated Press story at the time. She was charged with four counts of risk of injury to a minor, but after her sentencing was delayed four times, her conviction was thrown out and a new trial granted.

This week, facing health problems, Amero pleaded guilty to one count of misdemeanor disorderly conduct, paying a $100 fine and losing her teaching license, just to settle the case.

As it turned out, not only was the computer in question unprotected by firewall, antispyware, or pop-up blocking software -- because the district hadn't paid for updates -- but the prosecution hadn't checked the computer for malware, nor would it allow the defense to present evidence of that, because the defense team had not raised it as a possibility early enough during trial preparation, and the prosecution's expert witness was not skilled in that type of forensic research.

In comparison, when a Virginia teacher showed a videotape to a fourth-grade classroom that suddenly turned into pornography, the school district focused instead on how the problem happened -- which the district decided was due to an incomplete tape erasing before the copying process. Nobody -- least of all the teacher -- was charged with any crime.

Certainly it's important to ensure that children are protected from seeing pornography. On the other hand, it's also important to make sure that the police and prosecutors have the appropriate level of skill and technology to find out how a problem actually happened.