Fear of Inadequacy
Jealousy among employees, or a fear of inadequacy, can sometimes cause an attitude problem with the employee that feels threatened, according to the article titled "How to Handle Difficult Behavior in the Workplace" published on the Mediate website. An employee may feel that his skill set is not adequate enough to perform at the same level as his co-workers, and this causes conflict and an attitude problem that can become pervasive. Talk with the troubled employee and ask if they feel they would benefit from further training. See if you can arrange to have the employee train with people within the company, and recommend training material the employee can look into outside of the office.
Personal Problems
When people feel pressured in many different aspects of their life, they sometimes lash out in non-productive ways, so says the article titled "Approaching Worker Attitude Problems" published on the HR Tools website. If an employee seems to be having problems communicating with co-workers, sit the employee down and ask them why they are being difficult. Try to avoid being confrontational. If you offer the employee a sympathetic ear, you may find that the problems stem from personal issues that have nothing to do with the workplace, but because so much time is spent at work the frustration boils over in the form of a bad attitude. While you do not want to try to get involved in an employee's personal life, you may be able to help re-arrange some work responsibilities while the employee attends to their personal matters. You could even suggest some paid time off if the employee has the vacation time, or unpaid if they do not, to allow the employee time to work out their issues.