Here is a crash log I got from trying to run update 43 TB 3. IT cant be my account for I'm logged in and everything....

---- Minecraft Crash Report ----

*** ATTENTION: detected classes with unsupported format ***

*** DO NOT SUBMIT THIS CRASH REPORT TO FORGE ***

Contact authors of the following mods: 

  thedalekmod

WARNING: coremods are present:

Contact their authors BEFORE contacting forge

// Oops.

Time: 4/22/16 11:31 PM

Description: Initializing game

java.lang.NoClassDefFoundError: com/swdteam/api/main/API

at uk.co.swdteam.client.init.DMSWDTeamAccount.isLoggedIn(DMSWDTeamAccount.java:14)

at uk.co.swdteam.client.eventHandler.TickHandler.initGuiEvent(TickHandler.java:537)

at net.minecraftforge.fml.common.eventhandler.ASMEventHandler_43_TickHandler_initGuiEvent_InitGuiEvent.invoke(.dynamic)

at net.minecraftforge.fml.common.eventhandler.ASMEventHandler.invoke(ASMEventHandler.java:55)

at net.minecraftforge.fml.common.eventhandler.EventBus.post(EventBus.java:140)

at net.minecraft.client.gui.GuiScreen.func_146280_a(GuiScreen.java:500)

at net.minecraft.client.Minecraft.func_147108_a(Minecraft.java:934)

at net.minecraft.client.Minecraft.func_71384_a(Minecraft.java:501)

at net.minecraft.client.Minecraft.func_99999_d(Minecraft.java:325)

at net.minecraft.client.main.Main.main(SourceFile:120)

at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)

at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)

at java.lang.reflect.Method.invoke(Method.java:606)

at net.minecraft.launchwrapper.Launch.launch(Launch.java:135)

at net.minecraft.launchwrapper.Launch.main(Launch.java:28)

Caused by: java.lang.ClassNotFoundException: com.swdteam.api.main.API

at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:191)

at java.lang.ClassLoader.loadClass(ClassLoader.java:425)

at java.lang.ClassLoader.loadClass(ClassLoader.java:358)

... 16 more

Caused by: java.lang.UnsupportedClassVersionError: com/swdteam/api/main/API : Unsupported major.minor version 52.0

at java.lang.ClassLoader.defineClass1(Native Method)

at java.lang.ClassLoader.defineClass(ClassLoader.java:803)

at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)

at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:182)

... 18 more

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

---------------------------------------------------------------------------------------

-- Head --

Stacktrace:

at uk.co.swdteam.client.init.DMSWDTeamAccount.isLoggedIn(DMSWDTeamAccount.java:14)

at uk.co.swdteam.client.eventHandler.TickHandler.initGuiEvent(TickHandler.java:537)

at net.minecraftforge.fml.common.eventhandler.ASMEventHandler_43_TickHandler_initGuiEvent_InitGuiEvent.invoke(.dynamic)

at net.minecraftforge.fml.common.eventhandler.ASMEventHandler.invoke(ASMEventHandler.java:55)

at net.minecraftforge.fml.common.eventhandler.EventBus.post(EventBus.java:140)

at net.minecraft.client.gui.GuiScreen.func_146280_a(GuiScreen.java:500)

at net.minecraft.client.Minecraft.func_147108_a(Minecraft.java:934)

at net.minecraft.client.Minecraft.func_71384_a(Minecraft.java:501)

-- Initialization --

Details:

Stacktrace:

at net.minecraft.client.Minecraft.func_99999_d(Minecraft.java:325)

at net.minecraft.client.main.Main.main(SourceFile:120)

at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)

at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)

at java.lang.reflect.Method.invoke(Method.java:606)

at net.minecraft.launchwrapper.Launch.launch(Launch.java:135)

at net.minecraft.launchwrapper.Launch.main(Launch.java:28)

-- System Details --

Details:

Minecraft Version: 1.8

Operating System: Linux (i386) version 3.13.0-85-generic

Java Version: 1.7.0_95, Oracle Corporation

Java VM Version: OpenJDK Client VM (mixed mode), Oracle Corporation

Memory: 123127728 bytes (117 MB) / 467890176 bytes (446 MB) up to 523501568 bytes (499 MB)

JVM Flags: 5 total; -Xmx512M -XX:+UseConcMarkSweepGC -XX:+CMSIncrementalMode -XX:-UseAdaptiveSizePolicy -Xmn128M

IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0

FML: MCP v9.10 FML v8.0.99.99 Minecraft Forge 11.14.4.1577 Optifine OptiFine_1.8_HD_U_H2 14 mods loaded, 14 mods active

States: 'U' = Unloaded 'L' = Loaded 'C' = Constructed 'H' = Pre-initialized 'I' = Initialized 'J' = Post-initialized 'A' = Available 'D' = Disabled 'E' = Errored

UCHIJAmcp{9.05} [Minecraft Coder Pack] (minecraft.jar) 

UCHIJAFML{8.0.99.99} [Forge Mod Loader] (forge-1.8-11.14.4.1577.jar) 

UCHIJAForge{11.14.4.1577} [Minecraft Forge] (forge-1.8-11.14.4.1577.jar) 

UCHIJAArchitectureCraft{1.2.1} [ArchitectureCraft] (ArchitectureCraft-Mod-1.8.jar) 

UCHIJAgrim3212core{V0.1 - 1.8} [Grim3212 Core] (Grim3212-Core-1.8.jar) 

UCHIJAbackpacksmod{V0.1 - 1.8} [Backpacks] (Backpacks-mod-by-grim3212-1.8.jar) 

UCHIJAthedalekmod{Update 43 TB3} [thedalekmod] (Dalek Mod Update 43_TB3.jar) 

UCHIJAfancypack{V0.1 - 1.8} [Fancy Pack] (FancyPack-Mod-1.8.jar) 

UCHIJAgravitycontrol{V0.1 - 1.8} [Gravity Controller] (Gravity-Control-Mod-1.8.jar) 

UCHIJAMultiPageChest{1.3.5} [Multi Page Chest] (Multi-Page-Chest-Mod-1.8.jar) 

UCHIJAoceancraft{1.5.1} [Oceancraft] (OceanCraft-Mod-1.8.jar) 

UCHIJAsoundfilters{0.8_for_1.8} [Sound Filters] (Sound-Filters-Mod-1.8.jar) 

UCHIJAVersionChecker{1.2.4} [Version Checker] (VersionChecker-1.2.4.jar) 

UCHIJAworldedit{6.1} [WorldEdit] (worldedit-forge-mc1.8-6.1.jar) 

Loaded coremods (and transformers): 

GL info: ' Vendor: 'Intel Open Source Technology Center' Version: '2.1 Mesa 10.1.3' Renderer: 'Mesa DRI Intel(R) 965GM x86/MMX/SSE2'

Launched Version: 1.8-forge1.8-11.14.4.1577

LWJGL: 2.9.1

OpenGL: Mesa DRI Intel(R) 965GM x86/MMX/SSE2 GL version 2.1 Mesa 10.1.3, Intel Open Source Technology Center

GL Caps: Using GL 1.3 multitexturing.

Using GL 1.3 texture combiners.

Using framebuffer objects because ARB_framebuffer_object is supported and separate blending is supported.

Shaders are available because OpenGL 2.1 is supported.

VBOs are available because OpenGL 1.5 is supported.

Using VBOs: Yes

Is Modded: Definitely; Client brand changed to 'fml,forge'

Type: Client (map_client.txt)

Resource Packs: []

Current Language: English (US)

Profiler Position: N/A (disabled)

try using this format here:      How to format bug reports

I think the problem is you have mods on that might not be compatible (Ex. Oceancraft, Backpacks Mod, MultiPage Chest. etc.)

Just found the cause of the issue, i'm patching at the moment and will release a new TB to fix it.