To dream of a desk represents your focus on evaluating a problem, figuring something out, or considering options. There may be an issue that you are interested in paying attention to.
To dream of sitting at a desk bored, or not concerned with anything serious may reflect an unpleasant situation you feel forced to think about. It may also be a sign that you need to be more serious or try harder to deal with problems.
To dream of sitting at someone else’s desk represents your interest in paying attention to an issue through a different perspective, or though some aspect of your personality.