Do you have a dehumidifier inthe basement? I've had one for years, and it failed about 3 weeks ago. Within a week, the basement smelled musty and I could see mold starting to form on the boxes. We bought a new one at Lowes (large capacity) for about $200. In 3 days, the basement smelled much better, and the humidity dropped from 95% to 80%, and it's still dropping. I typically set it at 60%.
Even if it doesn't feel damp, high humidity might not be helping your situation. Good luck!