That's what happen when someone take the hovering boxes when you on another tab. you still can see it but can't take it, it wont happen if you don't switch tabs while playing.
Very rare to get all 3 of those in 1 place lol. Two in one place is fairly common but all 3 hardly ever happens lol.
http://shellshockliveforums.com/index.php?threads/ghost-boxes.2229/ Original post of ghost boxes... Its a really common bug or glitch idk >:O
This is the first box on the ground that ive seen that couldnt be taken. Everyone saw it and i wasnt on another tab either. Very wierd indeed.