Hi There,I have a real concern here.About 2 years ago I had 17x17 porcelain tiles installed in my kitchen,living room,dining room,foyer and hall, a few months later I noticed when I dropped something I heard a hollow sound. In all the rooms that were done there are 166 tiles that are hollow like this. One tile in the center of my living room is rocking back and forth when I walk on it.I have called and discussed this with the contractor and he says he has no clue as to what the problem might be. The tiles surrounding this rocking tile is starting to rock slightly. To make matters worse to all this; is when the contractor installed the tiles there were asbestos tiles on the floor in the living room,dining room and hall. (this home was built in 1957 and the tile was original) He told me the best way to do this is to just go over the tiles with the porcelain tiles,this would seal them and that would be the end of that problem. Needless to say, if the porcelain tiles are hollow and at this point a few loose, what should I do now. I have an astmatic daughter and I have heard that asbestos in the air is not good for her or anyone as a matter of fact. This contractor keeps giving me the runaround and I think he is biding his time until the warranty runs out.Please if you can give me some expertise on this It would be gratefully appreciated.