In a perfect world your swimming pool will always run flawlessly and you will never have a technical problem, but if you do it's imperative to address it as quickly as possible.
Here's a couple of things you never want to let drag on if you suspect a problem:
A noisy pool pump. If the pump is running hot or is noisy something is definitely wrong and you should immediately shut the motor off to prevent damage. Don't use the pump or the swimming pool until you get it checked out by a professional. Also, if you hear noises from the pump, it could be an indication that the bearings are going bad and you should call a pool service technician to take a look and they might have to replace a few parts to get your pump back on track.
If you don't live on the beach and there's no chance a high wind kicked up and dropped sand in your pool, there is a problem. The sand is likely coming from the filter and should be addressed. The problem could be caused by an over-sized swimming pool pump or from a cracked lateral in the filter. However, the problem could be much simpler such as having too much sand in the filter. Again, your safest bet would be to contact a pool technician to look at the filter and offer a diagnosis.
While it's usually rare to run into pool problems you want to make sure that if you have one you have a professional check into it and help get you back on track so you and your family can jump back into the pool and keep enjoying it!