Anyone who has even had employees can tell you about this. The guy has been with you for a long time and has been an ideal employee. Gets to work on time, does a great job, has the motivation and skills needed to work independently and can be counted on to go the extra mile when circumstances call for it.
But suddenly, he just collapses. He starts coming in late or has a poor attitude about the job, starts dissing clients and spends time complaining to other employees, costing you time and productivity.
This creates a dilemma for you as the employer. You can call the guy on the carpet, tell him whatever you want. But that just seems to make things even worse. You can ignore the situation, hoping that it will pass. You can try and get the guy to talk about whatever is going on in his life that has caused him to do an about face. Maybe he is having problems at home or experienced some loss that has caused him to become depressed. If the employee is open to this approach, he may confide in you. More often than not, he is not really even aware of what is causing the problem. He may be drinking or doing drugs to help him deal with whatever the problem is.
You, as the employer, need to realize that you are not a therapist or a counselor and while you may be willing to work with a troubled employee, that is not the reason either of you are there. If the employee is valued enough, you may be able to help him get whatever he needs to make a course correction. But, many times these situations just go from bad to worse and end with the termination of the employee.
Over the next week, I will suggest some techniques for dealing with this that may or may not produce the desired result which is to get the employee back on track with as little time and productivity loss as possible.