Error occurred when you I tried to to put mining laser with few other tools (electric wrench, diamond tipped drill, some cables etc.) in toolbox. Game crashed right after using toolbox.
While trying to recreate bug I got rid of bugged toolbox and tried to store different tools without laser and it works fine. Then repeat the same with mining laser and tools crash again. Another attempt was to store just mining laser without other stuff and it was possible to close mining laser inside toolbox alone. Then again with some tools and without others. It looks like bug happens kinda randomly at this point. Sometimes game crashes while getting stuff out of toolbox and sometimes while putting it in there but it's always somehow related to mining laser.
Also after getting in the same game items are getting multiplied. Picture under spoiler.
Mods loaded: 4
ModLoader 1.2.4
mod_ModLoaderMp 1.2.4v1
mod_MinecraftForge 2.0.0.67
mod_IC2 v1.90
Minecraft has crashed!
----------------------
Minecraft has stopped running because it encountered a problem.
--- BEGIN ERROR REPORT 27192b5c --------
Generated 08.04.12 17:44
Minecraft: Minecraft 1.2.4
OS: Windows 7 (x86) version 6.1
Java: 1.6.0_31, Sun Microsystems Inc.
VM: Java HotSpot(TM) Client VM (mixed mode), Sun Microsystems Inc.
LWJGL: 2.4.2
OpenGL: ATI Radeon HD 5700 Series version 4.2.11554 Compatibility Profile Context, ATI Technologies Inc.
java.lang.ArrayIndexOutOfBoundsException: 8
at ic2.common.ItemToolbox.unpack(ItemToolbox.java:146)
at ic2.common.ItemToolbox.a(ItemToolbox.java:81)
at aan.a(SourceFile:98)
at ki.a(PlayerController.java:77)
at net.minecraft.client.Minecraft.c(Minecraft.java:1401)
at net.minecraft.client.Minecraft.k(Minecraft.java:1817)
at net.minecraft.client.Minecraft.x(Minecraft.java:842)
at net.minecraft.client.Minecraft.run(Minecraft.java:747)
at java.lang.Thread.run(Unknown Source)
--- END ERROR REPORT 85445c5f ----------