There are 2 problems that I see here. They are very separate, but both equally important.
As @Matthieu has suggested it appears that you have a bad employee, the type that are not only non-productive (zero impact), but are a negative impact on progress and the team (morale, fusion / gelling, friendliness). You need to understand why this employee was hired. If it is a HR error, or a competent liar during the interview, then you can most likely resolve it by recommending to your management (or their boss) the termination of this employee's employment as a programmer. Perhaps they are a competent IT system administrator and perplexed why they are being asked to do programming. -- I've had job interviews through recruitment agencies that were about as messed up (on purpose by the agency) in the past, so it may not be the employee's fault.
But there may be office politics, such as a relationship to senior staff / executives that you may need to know about before making noise. This you need to do quietly before saying anything to anyone other than your manager / supervisor. In that case you could need to develop a containment strategy which is primarily isolation (problem containment) and damage control.
Then, the second issue, if you end up keeping this employee then you need to give them their own environment where they can safely learn and progress, mistakes and all, in a healthy positive environment that can hopefully groom a potential programmer. This means they do need "real" projects eventually. An employee who clearly knows they are being isolated becomes even more disenfranchised and demotivated. You need to create a miniature "career development" strategy for this employee. What would it take to get them to become a useful employee in the future? Typically starting with education and/or training. Combined with developing a sense of basic skills in the work place (often called work ethic).
You don't mention age explicitly, but I'm going to assume that hopefully this employee is young as well as new, and thus most likely inexperienced, and can be encouraged to learn how to get along in the workplace. HR might be able to suggest "career development" training options that might be an opportunity for them to learn how they should act in the workplace. Larger employers may have some in-house options even. Human Resources can often help here.
I believe you are on the right track that something is amiss, and that you need to gather future information before taking action.
Another action I would also take, is sit down with the employee and ask them about themselves, so you know more about their background and experience. Family connections will tend to be mentioned if that is the basis of employment.
Best of luck.