Is this buildup of moisture all around the exterior walls or is it in one or two locations?
Is it on the entire wall or just the top, bottom, middle, etc. ?
Do your windows also have a buildup of condensation?
... Trying to determine if the moisture is coming through the walls or condensing on the walls.
If the moisture is coming throught the outside and it is only in isolated spots, I might suspect a leak in the roof. The leak may not be directly above the water problem - the water could be travelling quite a distance under the shingles before it drops down to the walls. If you have access to the attic, look for water spots on the roof sheathing.
Post again with some more details about the size and shape of the moisture.