Here is an excerpt from an article written by Rosabeth Moss Kanter for the Harvard Business Review blog. To read the complete article, check out the wealth of free resources, and sign up for a subscription to HBR email alerts, please click here.

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In a volatile world, anxiety and uncertainty make people a little testy.

Cranky people can drag everyone else down by spreading negativity and sowing seeds of doubt just when leaders need commitment. And when everyday crankiness is exacerbated by performance problems, then the merely grumpy can become disgruntled former employees out to do damage to the team.

Early in my career, when sharing a vacation house with a group of friends, I learned an important lesson from a classic book by anthropologist Mary Douglas, Purity and Danger: It takes a lot of people cooperating to keep things neat, but it takes only one disgruntled dirt-monger to mess things up. The task for everyone else is not to let them.

This has become a favorite management insight as I advise bosses and boards. In one recent case, the chief financial officer of a small company was fired for possible expense account violations, and he was also seen as a poor strategist and weak team player. The former CFO did not go quietly. He consulted a lawyer, then went to a second and a third when the first one said he didn’t have a case. He rallied friends who sent emails to prominent customers about his grievance. Meanwhile, the CEO and new CFO had to raise capital and revenues to make up for the shortfall, which the disgruntled former CFO blamed on everyone else. His loud voice and tale of mistreatment threatened to topple the entire enterprise.

When faced with cranky, grumpy, or disgruntled people, these Do’s and Don’ts can be helpful.

[Here are five of the nine. To read the complete article, please click here.]

1. Don’t give them power. Don’t let their claims occupy disproportionate time and management attention. Have one person manage so that everyone else can continue the real work.

2. Do keep telling your positive story about the organization’s purpose, mission, goals, and accomplishments. Remind everyone about the big picture.

3. Don’t adopt an angry tone. Stay calm and professional. Don’t stoop to their level by telling juicy stories. Recent studies show that badmouthing makes the tale-teller look bad, in a boomerang effect.

4. Don’t tell their story for them. Don’t start meetings or conversations by rehashing the situation. Stick to a simple statement or two that acknowledges your sorrow that there are complaints. Don’t sound defensive. Don’t lend credibility by providing your answers to things that audiences might not know or care about.

5. Don’t assume that being right is enough. Having the facts on your side might be enough in a court of law, but it is not necessarily enough in the court of public opinion. Other people are convinced by your actions. They need to see that you operate by principles. They will judge your authenticity and consistency.

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Above all, do what’s right for the mission and stakeholders. Even in a volatile world that requires tough decisions, the best way to counter crankiness is through an inspiring, energizing purpose.

[Note: I cannot resist citing again what Herb Kelleher, former chairman and CEO of Southwest Airlines, said when explaining the airline’s spectacular success: “We take great care of our people, our people take great care of our customers, and our customers take great care of our shareholders.”]

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Rosabeth Moss Kanter is a professor at Harvard Business School and the author of Confidence and SuperCorp. Connect with her on Facebook or at Twitter.com/RosabethKanter.