What do you mean by ‘problem’?
A problem is something which gives rise to human thought—such as a conflict between two theories, a paradox or anomaly. It does not only refer to ‘bad problems’—conflicts between people, problems that seem to make people miserable, things we would rather avoid. Anything sparking thinking, including enormously enjoyable thinking, like when you notice something and wonder about it, following your curiosity wherever it leads, is a ‘problem’ in this wide sense.