You may already know that there are problems with the nexus, but whenever I put something inside of it my game crashes and I can't load my world again without it crashing. Another thing is that when I have about a hundred or so clay soldiers spawned and they are all collecting items at once, my game will crash and continue to do so. I basically spawn in 80 soldiers, throw out a stack or two of leather, the game has no problem, a few seconds later it lags for a second and then crashes. I have fully updated java 7 and am on 1.7.10 with the latest forge update and clay soldiers update. If I need to copy the crash report here just tell me and I will do so.
Edit: I apologize forgetting to label this a bug.

Need logs

I am no longer able to replicate the clay soldiers crashing the game in large numbers while gathering resources, although I was able to a few days ago. I'll have to keep testing, but here is the crash report caused every time I try to place something in a nexus.

---- Minecraft Crash Report ----
// This doesn't make any sense!

Time: 2/7/15 11:20 AM
Description: Rendering Block Entity

java.lang.NoClassDefFoundError: de/sanandrew/core/manpack/util/client/ItemRenderHelper
at de.sanandrew.mods.claysoldiers.client.render.tileentity.RenderClayNexus.renderSoldierItem(RenderClayNexus.java:115)
at de.sanandrew.mods.claysoldiers.client.render.tileentity.RenderClayNexus.func_147500_a(RenderClayNexus.java:54)
at net.minecraft.client.renderer.tileentity.TileEntityRendererDispatcher.func_147549_a(SourceFile:100)
at net.minecraft.client.renderer.tileentity.TileEntityRendererDispatcher.func_147544_a(SourceFile:92)
at net.minecraft.client.renderer.RenderGlobal.func_147589_a(RenderGlobal.java:483)
at net.minecraft.client.renderer.EntityRenderer.func_78471_a(EntityRenderer.java:1224)
at net.minecraft.client.renderer.EntityRenderer.func_78480_b(EntityRenderer.java:1011)
at net.minecraft.client.Minecraft.func_71411_J(Minecraft.java:989)
at net.minecraft.client.Minecraft.func_99999_d(Minecraft.java:887)
at net.minecraft.client.main.Main.main(SourceFile:148)
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:135)
at net.minecraft.launchwrapper.Launch.main(Launch.java:28)
Caused by: java.lang.ClassNotFoundException: de.sanandrew.core.manpack.util.client.ItemRenderHelper
at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:191)
at java.lang.ClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
... 16 more
Caused by: java.lang.NullPointerException
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 de.sanandrew.mods.claysoldiers.client.render.tileentity.RenderClayNexus.renderSoldierItem(RenderClayNexus.java:115)
at de.sanandrew.mods.claysoldiers.client.render.tileentity.RenderClayNexus.func_147500_a(RenderClayNexus.java:54)

-- Block Entity Details --
Details:
Name: claysoldiers:nexus_te // de.sanandrew.mods.claysoldiers.tileentity.TileEntityClayNexus
Block type: ID #165 (tile.claysoldiers:nexus // de.sanandrew.mods.claysoldiers.block.BlockClayNexus)
Block data value: 0 / 0x0 / 0b0000
Block location: World: (-1158,4,1012), Chunk: (at 10,0,4 in -73,63; contains blocks -1168,0,1008 to -1153,255,1023), Region: (-3,1; contains chunks -96,32 to -65,63, blocks -1536,0,512 to -1025,255,1023)
Actual block type: ID #165 (tile.claysoldiers:nexus // de.sanandrew.mods.claysoldiers.block.BlockClayNexus)
Actual block data value: 0 / 0x0 / 0b0000
Stacktrace:
at net.minecraft.client.renderer.tileentity.TileEntityRendererDispatcher.func_147549_a(SourceFile:100)
at net.minecraft.client.renderer.tileentity.TileEntityRendererDispatcher.func_147544_a(SourceFile:92)
at net.minecraft.client.renderer.RenderGlobal.func_147589_a(RenderGlobal.java:483)
at net.minecraft.client.renderer.EntityRenderer.func_78471_a(EntityRenderer.java:1224)

-- Affected level --
Details:
Level name: MpServer
All players: 1 total; [EntityClientPlayerMP['8comimi'/21, l='MpServer', x=-1154.50, y=5.62, z=1012.50]]
Chunk stats: MultiplayerChunkCache: 618, 618
Level seed: 0
Level generator: ID 01 - flat, ver 0. Features enabled: false
Level generator options:
Level spawn location: World: (-1152,4,1015), Chunk: (at 0,0,7 in -72,63; contains blocks -1152,0,1008 to -1137,255,1023), Region: (-3,1; contains chunks -96,32 to -65,63, blocks -1536,0,512 to -1025,255,1023)
Level time: 349 game time, 349 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: 1 total; [EntityClientPlayerMP['8comimi'/21, l='MpServer', x=-1154.50, y=5.62, z=1012.50]]
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:373)
at net.minecraft.client.Minecraft.func_71396_d(Minecraft.java:2432)
at net.minecraft.client.Minecraft.func_99999_d(Minecraft.java:909)
at net.minecraft.client.main.Main.main(SourceFile:148)
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:135)
at net.minecraft.launchwrapper.Launch.main(Launch.java:28)

-- System Details --
Details:
Minecraft Version: 1.7.10
Operating System: Windows 7 (amd64) version 6.1
Java Version: 1.8.0_31, Oracle Corporation
Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
Memory: 180226632 bytes (171 MB) / 324317184 bytes (309 MB) up to 1060372480 bytes (1011 MB)
JVM Flags: 6 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx1G -XX:+UseConcMarkSweepGC -XX:+CMSIncrementalMode -XX:-UseAdaptiveSizePolicy -Xmn128M
AABB Pool Size: 0 (0 bytes; 0 MB) allocated, 0 (0 bytes; 0 MB) used
IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
FML: MCP v9.05 FML v7.10.85.1291 Minecraft Forge 10.13.2.1291 5 mods loaded, 5 mods active
mcp{9.05} Minecraft Coder Pack Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available->Available->Available
FML{7.10.85.1291} Forge Mod Loader Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available->Available->Available
Forge{10.13.2.1291} Minecraft Forge Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available->Available->Available
sapmanpack{2.3.0} SanAndreasPs Manager Pack CORE edition Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available->Available->Available
claysoldiers{2.0.0b} Clay Soldiers Mod Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available->Available->Available
Launched Version: 1.7.10-Forge10.13.2.1291
LWJGL: 2.9.1
OpenGL: GeForce GTX 750 Ti/PCIe/SSE2 GL version 4.4.0 NVIDIA 344.65, NVIDIA Corporation
GL Caps: Using GL 1.3 multitexturing.
Using framebuffer objects because OpenGL 3.0 is supported and separate blending is supported.
Anisotropic filtering is supported and maximum anisotropy is 16.
Shaders are available because OpenGL 2.1 is supported.

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

sapmanpack{2.3.0} SanAndreasPs Manager Pack CORE edition Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available->Available->Available
claysoldiers{2.0.0b} Clay Soldiers Mod Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available->Available->Available

Old versions in place here. That crash was fixed recently.

Since you can't reproduce the issue anymore (I assume you've updated), I'll close this down now. Feel free to reopen it if you can replicate it.