It’s tempting to ignore the constant gripes of a serial complainer. But that won’t make the problem go away.
Be ready for possible lawsuits by investigating, deciding what happened, disciplining if necessary and documenting the whole process.
Recent case: Felicia Ross sued her former employer after she walked out, fed up about harassment complaints she said were ignored. She had complained without success to managers and even the company president. The court said her lawsuit could go forward, and the employer would have to show how it handled her complaints. (Ross v. ITT Cleveland Motor Control, No. 1:09-CV-2220, ND OH, 2010)
Final note: Ross apparently couldn’t find an attorney and had to file her own lawsuit. That’s not always good for employers, since courts often bend over backward to help so-called pro se litigants.