It can be tempting to dismiss this sort of request out of hand because you're busy on something else, or you don't think it's your job to fix the problem. This would be bad diplomacy, and would generally only result in both parties getting annoyed with each other:
- Instead, appreciate that the other person is only trying to do their job, and whatever they've come to report, it's probably hindering them actually carrying on with the said job. The problem could be of their own design, or because of an issue you've missed in your infrastructure, but whatever the reason, it's important to handle the situation carefully.
- Even if you're not the point of contact for the issue in question, and you have no idea how you'd even start ...