I've got the same problem on my server. I wasn't logged in, when I checked the console, it was frozen, I rebooted and got this error message.
I have no clue what my users did, does anyone know the easiest fix for this?
2012-09-03 20:31:42 [sEVERE] java.lang.NullPointerException
2012-09-03 20:31:42 [sEVERE] at codechicken.wirelessredstone.addons.RedstoneEtherAddonManager.detonateREP(RedstoneEtherAddonManager.java:492)
2012-09-03 20:31:42 [sEVERE] at codechicken.wirelessredstone.addons.ItemREP.a(ItemREP.java:27)
2012-09-03 20:31:42 [sEVERE] at net.minecraft.server.ItemStack.a(ItemStack.java:97)
2012-09-03 20:31:42 [sEVERE] at eloraam.machine.TileDeployBase.tryUseItemStack(TileDeployBase.java:203)
2012-09-03 20:31:42 [sEVERE] at eloraam.machine.TileDeploy.enableTowards(TileDeploy.java:106)
2012-09-03 20:31:42 [sEVERE] at eloraam.machine.TileDeployBase.onBlockNeighborChange(TileDeployBase.java:250)
2012-09-03 20:31:42 [sEVERE] at eloraam.core.BlockExtended.doPhysics(BlockExtended.java:63)
2012-09-03 20:31:42 [sEVERE] at eloraam.core.RedPowerLib.notifyBlock(RedPowerLib.java:25)
2012-09-03 20:31:42 [sEVERE] at eloraam.core.RedPowerLib.updateCurrent(RedPowerLib.java:1220)
2012-09-03 20:31:42 [sEVERE] at eloraam.wiring.TileWiring.onBlockNeighborChange(TileWiring.java:243)
2012-09-03 20:31:42 [sEVERE] at eloraam.core.BlockMultipart.doPhysics(BlockMultipart.java:29)
2012-09-03 20:31:42 [sEVERE] at eloraam.core.RedPowerLib.notifyBlock(RedPowerLib.java:25)
2012-09-03 20:31:42 [sEVERE] at eloraam.core.RedPowerLib.updateIndirectNeighbors(RedPowerLib.java:48)
2012-09-03 20:31:42 [sEVERE] at eloraam.core.TileExtended.updateBlockChange(TileExtended.java:98)
2012-09-03 20:31:42 [sEVERE] at eloraam.logic.TileLogicPointer.timerUpdate(TileLogicPointer.java:219)
2012-09-03 20:31:42 [sEVERE] at eloraam.logic.TileLogicPointer.q_(TileLogicPointer.java:413)
2012-09-03 20:31:42 [sEVERE] at net.minecraft.server.World.tickEntities(World.java:1190)
2012-09-03 20:31:42 [sEVERE] at net.minecraft.server.MinecraftServer.w(MinecraftServer.java:569)
2012-09-03 20:31:42 [sEVERE] at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:467)
2012-09-03 20:31:42 [sEVERE] at net.minecraft.server.ThreadServerApplication.run(SourceFile:492)
2012-09-03 20:31:42 [sEVERE] Unexpected exception
java.lang.NullPointerException
at codechicken.wirelessredstone.addons.RedstoneEtherAddonManager.detonateREP(RedstoneEtherAddonManager.java:492)
at codechicken.wirelessredstone.addons.ItemREP.a(ItemREP.java:27)
at net.minecraft.server.ItemStack.a(ItemStack.java:97)
at eloraam.machine.TileDeployBase.tryUseItemStack(TileDeployBase.java:203)
at eloraam.machine.TileDeploy.enableTowards(TileDeploy.java:106)
at eloraam.machine.TileDeployBase.onBlockNeighborChange(TileDeployBase.java:250)
at eloraam.core.BlockExtended.doPhysics(BlockExtended.java:63)
at eloraam.core.RedPowerLib.notifyBlock(RedPowerLib.java:25)
at eloraam.core.RedPowerLib.updateCurrent(RedPowerLib.java:1220)
at eloraam.wiring.TileWiring.onBlockNeighborChange(TileWiring.java:243)
at eloraam.core.BlockMultipart.doPhysics(BlockMultipart.java:29)
at eloraam.core.RedPowerLib.notifyBlock(RedPowerLib.java:25)
at eloraam.core.RedPowerLib.updateIndirectNeighbors(RedPowerLib.java:48)
at eloraam.core.TileExtended.updateBlockChange(TileExtended.java:98)
at eloraam.logic.TileLogicPointer.timerUpdate(TileLogicPointer.java:219)
at eloraam.logic.TileLogicPointer.q_(TileLogicPointer.java:413)
at net.minecraft.server.World.tickEntities(World.java:1190)
at net.minecraft.server.MinecraftServer.w(MinecraftServer.java:569)
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:467)
at net.minecraft.server.ThreadServerApplication.run(SourceFile:492)