Is there a version somewhere that fixes the machines' API calls or disables API error messages?
Because spamming the console with "[WARNING] [IC2] API ERROR: ic2.core.block.machine.tileentity.TileEntityMacerator@7c96ade5 didn't implement demandsEnergy() properly, no energy from injectEnergy accepted although demandsEnergy() returned true." or similar is getting pretty ridiculous. I am getting dozens of messages per second.
I am getting this (server-side) error and kicked off the server when breaking Twilight Forest root strands with Chainsaw
2012-11-30 08:32:26 [SEVERE] [ForgeModLoader] A critical server error occured handling a packet, kicking 18006777
java.lang.NullPointerException
at ic2.common.ItemElectricTool.a(ItemElectricTool.java:178)
at um.a(SourceFile:196)
at ir.b(ItemInWorldManager.java:310)
at ir.a(ItemInWorldManager.java:193)
at iv.a(NetServerHandler.java:445)
at ej.a(SourceFile:46)
at cg.b(TcpConnection.java:451)
at iv.d(NetServerHandler.java:82)
at iw.b(NetworkListenThread.java:55)
at ht.b(SourceFile:30)
at net.minecraft.server.MinecraftServer.r(MinecraftServer.java:691)
at ho.r(DedicatedServer.java:252)
at net.minecraft.server.MinecraftServer.q(MinecraftServer.java:587)
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:494)
at fy.run(SourceFile:856)
2012-11-30 08:32:26 [WARNING] [Minecraft] Failed to handle packet for Quantux/80.220.13.160: java.lang.NullPointerException
java.lang.NullPointerException
at ic2.common.ItemElectricTool.a(ItemElectricTool.java:178)
at um.a(SourceFile:196)
at ir.b(ItemInWorldManager.java:310)
at ir.a(ItemInWorldManager.java:193)
at iv.a(NetServerHandler.java:445)
at ej.a(SourceFile:46)
at cg.b(TcpConnection.java:451)
at iv.d(NetServerHandler.java:82)
at iw.b(NetworkListenThread.java:55)
at ht.b(SourceFile:30)
at net.minecraft.server.MinecraftServer.r(MinecraftServer.java:691)
at ho.r(DedicatedServer.java:252)
at net.minecraft.server.MinecraftServer.q(MinecraftServer.java:587)
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:494)
at fy.run(SourceFile:856)I got the same error.
2011-12-30 01:23:58 [SEVERE] Unexpected exception
java.lang.NullPointerException
at jb.a(SourceFile:181)
at ic2.common.ItemArmorQuantumSuit.performQuantum(ItemArmorQuantumSuit.java:46)
at mod_IC2.OnTickInGame(mod_IC2.java:1537)
at ic2.platform.Ic2.OnTickInGame(Ic2.java:41)
at ModLoader.OnTick(ModLoader.java:772)
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:329)
at cu.run(SourceFile:457)I am using IC2 1.43, BC 2.2.11, RedPower PR4b, Minefactory Reloaded and Power Converters. Forge version is 1.2.3.
Eh.. Sorry. Nevermind, there already was a thread on this. 
I got the following error yesterday with a server crash. I don't know what the players were doing because I wasn't on at the time.
2011-12-30 01:23:58 [SEVERE] Unexpected exception
java.lang.NullPointerException
at jb.a(SourceFile:181)
at ic2.common.ItemArmorQuantumSuit.performQuantum(ItemArmorQuantumSuit.java:46)
at mod_IC2.OnTickInGame(mod_IC2.java:1537)
at ic2.platform.Ic2.OnTickInGame(Ic2.java:41)
at ModLoader.OnTick(ModLoader.java:772)
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:329)
at cu.run(SourceFile:457)I am using IC2 1.43, BC 2.2.11, RedPower PR4b, Minefactory Reloaded and Power Converters. Forge version is 1.2.3.