Why do my hardwood floors make a pop and cracking sound when walking across them? They are installed over a slab with the padding between. They are about 7 yrs old, and have made this noise ever since we bought house 6 yrs ago. Is there any way to fix without replacing? Also in the hall there are space in between the boards. How to fix this? Thanks!

Over the years the wood has warped and shrunk. If it's REALLY bad you should replace the floors which is a little pricey and takes a bit of patience but not that hard. Otherwise, you could refinish the floors: http://www.ehow.com/how_1856_r...

note: the above instructions does not include the use of mineral spirits. Always after sanding and before stain or poly use a damp cloth with mineral spirits to pick up the fine dust left behind.