I have a brand new 50in. Plasma tv.. I have it set a few feet from under the heat vent in my room. I noticed when the vent comes on it makes a cracking noise.... It's only when the vent comes on. I read it has something to do with the heat from the tv making the molecules expand?? Anyways, just wondering if it's safe? Will it ruin my tv and should I place it someplace else? Will putting a blanket over it help?