Congratulations.Something similar happen to me today, someone stole the stabilizer bar and the rope to hold a ladder stand to the tree. They tried to take the ladder stand down, but I had it locked in. I took it down so it wouldn't get stolen, so now I am going to put in a cheap one of these for about $8. See this for how to make them:

http://www.the-gleasons.com/low_cost_tree_stands_for_hunting.htm

They won't be able to steal it, but I think it was hunter harrasment by the folks next door.
Chap Gleason