Please present a crash log of the incident, further help cannot be rendered if we do not have evidence to dissect and thus diagnose.

ok. doing some more tests. this only occurs when using optifine.

crash log:
---- Minecraft Crash Report ----
// I bet Cylons wouldn't have this problem.

Time: 08/10/13 14:57
Description: Rendering screen

java.lang.NullPointerException
at buildcraft.energy.gui.GuiEngine$EngineLedger.draw(GuiEngine.java:39)
at buildcraft.core.gui.GuiBuildCraft$LedgerManager.drawLedgers(GuiBuildCraft.java:84)
at buildcraft.core.gui.GuiBuildCraft.func_74189_g(GuiBuildCraft.java:307)
at buildcraft.energy.gui.GuiStoneEngine.func_74189_g(GuiStoneEngine.java:30)
at net.minecraft.client.gui.inventory.GuiContainer.func_73863_a(GuiContainer.java:150)
at buildcraft.core.gui.GuiBuildCraft.func_73863_a(GuiBuildCraft.java:249)
at net.minecraft.client.renderer.EntityRenderer.func_78480_b(EntityRenderer.java:1149)
at net.minecraft.client.Minecraft.func_71411_J(Minecraft.java:945)
at net.minecraft.client.Minecraft.func_99999_d(Minecraft.java:837)
at net.minecraft.client.main.Main.main(SourceFile:101)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at net.minecraft.launchwrapper.Launch.launch(Launch.java:131)
at net.minecraft.launchwrapper.Launch.main(Launch.java:27)

A detailed walkthrough of the error, its code path and all known details is as follows:

-- Head --
Stacktrace:
at buildcraft.energy.gui.GuiEngine$EngineLedger.draw(GuiEngine.java:39)
at buildcraft.core.gui.GuiBuildCraft$LedgerManager.drawLedgers(GuiBuildCraft.java:84)
at buildcraft.core.gui.GuiBuildCraft.func_74189_g(GuiBuildCraft.java:307)
at buildcraft.energy.gui.GuiStoneEngine.func_74189_g(GuiStoneEngine.java:30)
at net.minecraft.client.gui.inventory.GuiContainer.func_73863_a(GuiContainer.java:150)
at buildcraft.core.gui.GuiBuildCraft.func_73863_a(GuiBuildCraft.java:249)

-- Screen render details --
Details:
Screen name: buildcraft.energy.gui.GuiStoneEngine
Mouse location: Scaled: (213, 119). Absolute: (427, 240)
Screen size: Scaled: (427, 240). Absolute: (854, 480). Scale factor of 2

-- Affected level --
Details:
Level name: MpServer
All players: 1 total; [EntityClientPlayerMP['Notuz'/399, l='MpServer', x=169,57, y=72,62, z=266,21]]
Chunk stats: MultiplayerChunkCache: 441
Level seed: 0
Level generator: ID 00 - default, ver 1. Features enabled: false
Level generator options:
Level spawn location: World: (166,64,255), Chunk: (at 6,4,15 in 10,15; contains blocks 160,0,240 to 175,255,255), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511)
Level time: 655 game time, 655 day time
Level dimension: 0
Level storage version: 0x00000 - Unknown?
Level weather: Rain time: 0 (now: false), thunder time: 0 (now: false)
Level game mode: Game mode: creative (ID 1). Hardcore: false. Cheats: false
Forced entities: 81 total; [EntitySkeleton['Skeleton'/275, l='MpServer', x=224,16, y=52,00, z=212,50], EntitySkeleton['Skeleton'/274, l='MpServer', x=228,68, y=16,16, z=212,68], EntitySkeleton['Skeleton'/273, l='MpServer', x=228,66, y=16,00, z=215,34], EntitySkeleton['Skeleton'/272, l='MpServer', x=229,66, y=16,00, z=216,34], EntityChicken['Chicken'/279, l='MpServer', x=224,50, y=65,00, z=323,50], EntityBat['Bat'/278, l='MpServer', x=239,70, y=39,04, z=330,88], EntityZombie['Zombie'/277, l='MpServer', x=226,50, y=52,00, z=210,50], EntityCreeper['Creeper'/276, l='MpServer', x=231,03, y=45,00, z=219,50], EntityBat['Bat'/129, l='MpServer', x=171,70, y=41,00, z=196,69], EntityBat['Bat'/128, l='MpServer', x=163,50, y=43,62, z=187,49], EntityBat['Bat'/131, l='MpServer', x=151,47, y=56,94, z=200,76], EntityClientPlayerMP['Notuz'/399, l='MpServer', x=169,57, y=72,62, z=266,21], EntityBat['Bat'/133, l='MpServer', x=163,78, y=58,27, z=210,63], EntitySkeleton['Skeleton'/132, l='MpServer', x=157,56, y=59,00, z=212,03], EntityChicken['Chicken'/135, l='MpServer', x=156,06, y=64,00, z=273,09], EntityZombie['Zombie'/134, l='MpServer', x=156,56, y=25,72, z=249,75], EntityBat['Bat'/152, l='MpServer', x=164,12, y=58,00, z=211,08], EntityBat['Bat'/153, l='MpServer', x=171,63, y=36,86, z=222,10], EntityBat['Bat'/154, l='MpServer', x=173,91, y=47,10, z=205,59], EntityBat['Bat'/155, l='MpServer', x=169,64, y=56,77, z=217,46], EntityCreeper['Creeper'/156, l='MpServer', x=171,50, y=42,00, z=237,63], EntityBat['Bat'/157, l='MpServer', x=163,41, y=58,10, z=229,75], EntitySkeleton['Skeleton'/158, l='MpServer', x=175,50, y=55,00, z=229,50], EntitySkeleton['Skeleton'/159, l='MpServer', x=161,39, y=57,00, z=221,22], EntityZombie['Zombie'/147, l='MpServer', x=173,47, y=32,17, z=198,26], EntityBat['Bat'/148, l='MpServer', x=164,55, y=43,60, z=204,49], EntityPig['Pig'/271, l='MpServer', x=239,47, y=70,00, z=195,50], EntitySkeleton['Skeleton'/149, l='MpServer', x=171,44, y=58,00, z=201,94], EntitySkeleton['Skeleton'/150, l='MpServer', x=176,58, y=56,60, z=205,46], EntitySkeleton['Skeleton'/151, l='MpServer', x=165,48, y=57,54, z=214,49], EntityChicken['Chicken'/163, l='MpServer', x=165,38, y=67,00, z=266,63], EntityChicken['Chicken'/162, l='MpServer', x=176,64, y=66,00, z=255,84], EntityZombie['Zombie'/161, l='MpServer', x=174,50, y=63,00, z=227,50], EntitySkeleton['Skeleton'/160, l='MpServer', x=173,50, y=55,00, z=228,50], EntityCreeper['Creeper'/190, l='MpServer', x=176,50, y=43,00, z=230,50], EntityCreeper['Creeper'/191, l='MpServer', x=177,50, y=63,00, z=228,50], EntityZombie['Zombie'/188, l='MpServer', x=190,97, y=11,00, z=202,53], EntityCreeper['Creeper'/189, l='MpServer', x=176,50, y=43,00, z=229,50], EntityPig['Pig'/298, l='MpServer', x=243,75, y=68,00, z=201,25], EntityPig['Pig'/299, l='MpServer', x=235,36, y=73,00, z=194,49], EntityPig['Pig'/300, l='MpServer', x=241,97, y=69,00, z=204,63], EntityZombie['Zombie'/301, l='MpServer', x=248,50, y=22,00, z=328,50], EntityCreeper['Creeper'/302, l='MpServer', x=239,00, y=34,00, z=339,50], EntityCreeper['Creeper'/303, l='MpServer', x=245,69, y=32,00, z=336,69], EntityZombie['Zombie'/205, l='MpServer', x=205,50, y=71,00, z=207,50], EntityZombie['Zombie'/204, l='MpServer', x=197,03, y=12,00, z=194,63], EntitySkeleton['Skeleton'/207, l='MpServer', x=202,50, y=64,00, z=221,50], EntityZombie['Zombie'/206, l='MpServer', x=196,50, y=82,00, z=202,50], EntityChicken['Chicken'/201, l='MpServer', x=203,50, y=80,00, z=189,50], EntityChicken['Chicken'/200, l='MpServer', x=202,50, y=79,00, z=190,50], EntityZombie['Zombie'/203, l='MpServer', x=198,41, y=11,00, z=200,91], EntityChicken['Chicken'/202, l='MpServer', x=204,38, y=80,00, z=190,47], EntityChicken['Chicken'/199, l='MpServer', x=208,59, y=81,00, z=192,71], EntityBat['Bat'/78, l='MpServer', x=112,57, y=24,80, z=249,50], EntitySkeleton['Skeleton'/79, l='MpServer', x=112,38, y=24,00, z=252,71], EntityChicken['Chicken'/192, l='MpServer', x=179,44, y=68,00, z=264,63], EntityZombie['Zombie'/222, l='MpServer', x=218,50, y=14,00, z=192,50], EntityZombie['Zombie'/223, l='MpServer', x=218,50, y=14,00, z=193,50], EntityChicken['Chicken'/208, l='MpServer', x=204,47, y=83,00, z=213,59], EntitySkeleton['Skeleton'/89, l='MpServer', x=115,46, y=16,00, z=191,38], EntityCreeper['Creeper'/88, l='MpServer', x=122,72, y=22,00, z=190,06], EntityChicken['Chicken'/209, l='MpServer', x=205,53, y=82,00, z=215,03], EntitySkeleton['Skeleton'/210, l='MpServer', x=206,51, y=24,00, z=342,61], EntitySkeleton['Skeleton'/91, l='MpServer', x=116,50, y=25,00, z=250,44], EntitySkeleton['Skeleton'/90, l='MpServer', x=117,50, y=25,00, z=248,50], EntityItem['item.item.snowball'/238, l='MpServer', x=218,28, y=64,13, z=327,31], EntityCreeper['Creeper'/103, l='MpServer', x=139,25, y=31,00, z=197,88], EntityItem['item.item.snowball'/237, l='MpServer', x=216,06, y=64,13, z=330,81], EntityItem['item.item.snowball'/235, l='MpServer', x=217,81, y=64,13, z=329,41], EntityItem['item.item.snowball'/232, l='MpServer', x=216,81, y=64,13, z=330,34], EntityItem['item.item.snowball'/231, l='MpServer', x=218,81, y=64,13, z=328,19], EntityChicken['Chicken'/229, l='MpServer', x=222,50, y=65,00, z=322,50], EntityChicken['Chicken'/228, l='MpServer', x=220,50, y=65,00, z=322,50], EntitySkeleton['Skeleton'/106, l='MpServer', x=133,50, y=16,00, z=346,50], EntityChicken['Chicken'/227, l='MpServer', x=216,64, y=65,00, z=322,53], EntityCreeper['Creeper'/107, l='MpServer', x=134,50, y=16,00, z=342,50], EntityChicken['Chicken'/226, l='MpServer', x=215,46, y=77,00, z=200,24], EntitySkeleton['Skeleton'/104, l='MpServer', x=134,50, y=68,00, z=192,50], EntityChicken['Chicken'/225, l='MpServer', x=208,50, y=79,00, z=218,50], EntitySkeleton['Skeleton'/105, l='MpServer', x=136,50, y=31,00, z=218,50], EntityBat['Bat'/224, l='MpServer', x=216,75, y=27,10, z=208,25]]
Retry entities: 0 total; []
Server brand: fml,forge
Server type: Integrated singleplayer server
Stacktrace:
at net.minecraft.client.multiplayer.WorldClient.func_72914_a(WorldClient.java:440)
at net.minecraft.client.Minecraft.func_71396_d(Minecraft.java:2311)
at net.minecraft.client.Minecraft.func_99999_d(Minecraft.java:855)
at net.minecraft.client.main.Main.main(SourceFile:101)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at net.minecraft.launchwrapper.Launch.launch(Launch.java:131)
at net.minecraft.launchwrapper.Launch.main(Launch.java:27)

-- System Details --
Details:
Minecraft Version: 1.6.4
Operating System: Windows 7 (amd64) version 6.1
Java Version: 1.7.0_40, Oracle Corporation
Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
Memory: 212985136 bytes (203 MB) / 450363392 bytes (429 MB) up to 954728448 bytes (910 MB)
JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx1G
AABB Pool Size: 5045 (282520 bytes; 0 MB) allocated, 2058 (115248 bytes; 0 MB) used
Suspicious classes: FML and Forge are installed
IntCache: cache: 0, tcache: 0, allocated: 2, tallocated: 64
FML: MCP v8.11 FML v6.4.20.903 Minecraft Forge 9.11.0.903 Optifine OptiFine_1.6.4_HD_U_C5 9 mods loaded, 9 mods active
mcp{8.09} Minecraft Coder Pack Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available->Available->Available
FML{6.4.20.903} Forge Mod Loader Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available->Available->Available
Forge{9.11.0.903} Minecraft Forge Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available->Available->Available
BuildCraft|Core{4.1.0} BuildCraft Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available->Available->Available
BuildCraft|Builders{4.1.0} BC Builders Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available->Available->Available
BuildCraft|Energy{4.1.0} BC Energy Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available->Available->Available
BuildCraft|Factory{4.1.0} BC Factory Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available->Available->Available
BuildCraft|Transport{4.1.0} BC Transport Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available->Available->Available
BuildCraft|Silicon{4.1.0} BC Silicon Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available->Available->Available
Launched Version: 1.6.4-Forge9.11.0.903
LWJGL: 2.9.0
OpenGL: Intel(R) HD Graphics GL version 2.1.0 - Build 8.15.10.2827, Intel
Is Modded: Definitely; Client brand changed to 'fml,forge'
Type: Client (map_client.txt)
Resource Pack: Default
Current Language: English (US)
Profiler Position: N/A (disabled)
Vec3 Pool Size: 831 (46536 bytes; 0 MB) allocated, 414 (23184 bytes; 0 MB) used

Seems to be more reason to add a crashlog, while its most likely an Optifine issue its still nice to see these odd ones documented :)
EDIT: ah now I see the crashlog

I don't see Optifine in the loaded mods list near the end of the crashlog, did you install it directly or add it to the mods folder? (it can now be added to the mods folder)

Other than that one question this is beyond me now, but it is somewhat more ready for someone more knowledgable about these errors.

Duplicate of #1256, #1251