I was using nei to search for items with the search key "blue". It look like the the bluegrass is making NEI to fail to display properly but also crash MC when you create a instance of this item.

Thank

http://pastebin.com/wb65zYS7

Partial call stack
java.lang.ArrayIndexOutOfBoundsException: 49023
2013-12-11 20:25:37 [Infos] [STDOUT] at mods.natura.client.GrassColorizerAlternate.getBlueGrassColor(GrassColorizerAlternate.java:23)
2013-12-11 20:25:37 [Infos] [STDOUT] at mods.natura.blocks.GrassBlock.func_71889_f_(GrassBlock.java:71)
2013-12-11 20:25:37 [Infos] [STDOUT] at net.minecraft.client.renderer.RenderBlocks.func_78600_a(RenderBlocks.java:7637)
2013-12-11 20:25:37 [Infos] [STDOUT] at net.minecraft.client.renderer.ItemRenderer.renderItem(ItemRenderer.java:94)

try this in a launcher other than magiclauncher