Palmer Valve: In some homes where the drain tiles meet the floor drain you will find a Palmer Valve. This is a valve -like door that only opens one way. It allows water from the drain tile in to the floor drain. Sometimes it can stick, causing water to back up through floor cracks and around the edges. Check to see that it is working freely or have your plumber do it.
Wall Cracks: All residential basements have some cracks which are perfectly normal and are a result of original settlement and/or shrinkage of construction materials. These cracks may have a tendency to open and close slightly with the changes in temperature and are no cause for alarm. However, any horizontal crack in a concrete block wall is a result of a wall's inability to withstand external forces. Many of these walls require reinforcement that should be done by a professional.