Bukkit

What steps will reproduce the problem?
1. Make empty world
2. Make creative region
3. Let a player fly outside this region

What is the expected output? What do you see instead?
Player gets a message or something, imforming him he should stay on the ground when leaving a creative region

What version of the product are you using?
2.3-SNAPSHOT-06e08c630e

Do you have an error log of what happened?
Server crashes, infinity loop

Please provide any additional information below.
When a player leaves a creative region the plugin tries to find the next highest block to that player.
If there are no blocks under the player the plugin keeps searching forever (for example in an empty world).