I want to finish the basement but the concrete floor has two large cracks. The contractor told me that this was natrual to the house settling. I now see gray power on the edges of the cracks is this bad? What should I do??

Can you send pics? How old is the house?

The house will be 6 yrs in December. The cracks have been there from day one. It's maybe an 1/8 to 1/16 inch wide. The basement is 2900 sq ft but the cracks are on only one side of the house.

Here are some things I would check first because you said you have a crack about an 1/8 of inch, right?

Foundation cracks in this location.
Uneven floor by the cracks.
How much it has changed since you moved in.
I am guessing that you have drain tile/sump pump, am I correct?

While it is true that concrete cracks, how, and where is important to pay attention to.

I do know that you can use filler/seal the cracks as well. How do you plan on finishing the floor?

The cracks are there since the house was built. The builder inform me that when the concrete was poured, they neglected to divide into quarters. They divided it in half and within the half is the crack. It has not changed since the inception.

The grey powder is probably effervesence. A reaction betwwn moisture and cement.

You can fill in the cracks. I am guessing you have had no water problems up to this point.

I would be sure, however that if you lay floor down such as floating laminate or wood that you use a heavy vapor barrier before laying the padding and floor.

If you lay carpet, or something else, then you will need to prep the floor accordingly.

Concrete will crack, and particularly if the concrete wasn't lay properly to allow for expansion, but it still can crack. I have no cracks in my floor, even though my house is quite a bit older, but it does happen. As long as there is no heaving, or other problems associated with those cracks, just fill them and prep the floor to according to what type of flooring you will have.