This only happens when your trying to go on offline mod, but the place i'm in just had to reset their internet without notifying anyone, So is there any other way to get this message off your screen without restarting?
java.lang.IllegalArgumentException: Slot 242 is already occupied by thaumcraft.BlockConduit@5af1cf78 when adding ic2.common.BlockRubLeaves@396bfded
at oe.<init>(Block.java:176)
at oe.<init>(Block.java:204)
at jq.<init>(SourceFile:10)
at ic2.platform.BlockLeavesBaseCommon.<init>(BlockLeavesBaseCommon.java:12)
at ic2.common.BlockRubLeaves.<init>(BlockRubLeaves.java:25)
at mod_IC2.initialize(mod_IC2.java:255)
at ic2.platform.Ic2.load(Ic2.java:65)
at ModLoader.init(ModLoader.java:824)
at ModLoader.AddAllRenderers(ModLoader.java:189)
at afq.<init>(afq.java:80)
at afq.<clinit>(afq.java:9)
at net.minecraft.client.Minecraft.a(Minecraft.java:316)
at net.minecraft.client.Minecraft.run(Minecraft.java:624)
at java.lang.Thread.run(Unknown Source)