Corrosion on clear zinc plating

Recently a customer brought to my attention that a clear zinc chassis we have been building for them has started to develop corrosion(white.) The chassis' are isolated in a computer lab environment. At first I suspected that it was the plating process. But even the zinc plated screws that hold the thing together are even corroding. There aren't any of seams in the parts that could catch the plating. The only other thing I could think of is that there is excessive moisture in the air?

Any thoughts?

Has the chassis been exposed to temperatures over 200 degrees Fahrenheit? High temps destroy the chromate passivation and will cause early white corrosion.

Is there any acid in this room? Acidic vapors can attack anything metallic in the room and cause rust. An open container of acid on the other side of the room may be enough.