We have a terrible musty smell in our basement. We are in the process of finishing the basement and have never smelled anything before. There is no dampness, leakage or obvious problem. We have even been running 2 dehumidifiers all day and night and it has not touched the smell. I have looked everywhere and see no mold or mildew and the drywall, paneling and carpet is all new. It is just the awful smell! Please help, what can I do to get rid of the smell????