We’ve all been stuck in a boring meeting where someone was droning on and on while we thought about all the things we could be accomplishing if we weren’t stuck in a boring meeting. When called to a faculty meeting, college ecology professor Robert O. Lawton had the foresight to bring his manuscript. As other participants debated tenure issues, he quietly worked on his book about trees. The last thing he expected was that another professor would end the boredom by pulling an automatic weapon and opening fire.

When the shooting stopped, three of Lawton’s colleagues at the University of Alabama in Huntsville were dead and three others wounded. “It was an ordinary faculty meeting,” Lawton told reporters. “And then it became unordinary.”

Unfortunately, Lawton’s “unordinary” experience isn’t all that unordinary.

Though we’re less than two months into 2010, the UAH killings aren’t even the first by a disgruntled American worker this year. Nearly 700 people were murdered in their workplace in 2009. More than two million workplace assaults, including rapes and homicides, are reported each year, according to the Bureau of Labor Statistics—and it’s been estimated the actual number of assaults may be up to five times higher. And workplace violence isn’t a uniquely American problem.

You’d like to hope your bosses would take measures to protect you from dangerous customers and coworkers. But the truth is most companies don’t act until it’s too late. So it might help if you could at least spot some of these warning signs that people may have the potential to become violent:

• Playing the victim. You’ve met these folks: It’s never their fault. If they can’t meet a deadline, their coworkers screwed up. If they cheat in their marriage, their spouse is to blame. Life is a grand conspiracy theory, and they’re the hapless victim of their bosses, the government, the IRS—you name it. No, actually, they’ll name it.

• Acting out. These are the people who storm out of meetings, slamming the door behind them. They yell, scream, call names, throw things, kick over garbage cans, and practice their boxing moves on walls and doors. Their behavior is infantile and abusive.

• Demanding compliance. “It’s my way or no way!” You know the type: No compromise. They’re incapable of playing well with others and insist on micromanaging every detail of every project in which they’re involved. Everyone has to play by their rules or suffer the consequences.

• Avoiding reality. These individuals sidestep their responsibilities by lying, passing the buck, or numbing the pain with drugs and alcohol.

• Being antisocial. Yes, some people are quirky. But if you work with people whose quirks include failing to bathe, wash their clothes, wear deoderant, and brush their hair … or staring at someone for long periods, refusing to acknowledge when others speak to them, and so forth … you should be concerned. These behaviors are beyond quirky and eccentric. And if an otherwise unremarkable colleague suddenly begins exhibiting these behaviors, that’s cause for alarm.

While we all occasionally blame others for our mistakes, throw tantrums, get stubborn, or have bad hair days, people who consistently engage in these behaviors have deeper problems.