When using id 95 (Locked chest) in a preset, the game crash as you click "Use Preset".
This crash does not occur on 1.6.2.

Step to reproduce :
-Go into "Singleplayer" -> "Create New World"
-Click on "More World Options"
-Choose world type : "Superflat"
-Click on "Customize" -> "Presets"
-For example : change "2;7,2x3,2;1;village" to "2;7,2x3,2,95;1;village"
-Click on "Use Preset"
-The game should crash.