Hi...I've painted 2 rooms in my house this deep navy blue color. One room stays that color, in another room, over time I get this white wash filmy matter over it like I've brushed it with chalk powder. I don't understand-- I've painted this room twice and it's happened both times. The only difference in this room over the other where it doesn't happen is in this room there is a window portable air conditioner. Any suggestions on what is causing this? Lowe's told me I didn't primer correctly, but why would 1 room have worked and not this one? That was the same paint. Any ideas sure appreciated. Thanks, Mark