---- Minecraft Crash Report ----
// Surprise! Haha. Well, this is awkward.

Time: 5/1/14 10:00 AM
Description: Exception in server tick loop

java.lang.NoClassDefFoundError: scala/collection/Seq
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Unknown Source)
at cpw.mods.fml.common.ILanguageAdapter$ScalaAdapter.getNewInstance(ILanguageAdapter.java:21)
at cpw.mods.fml.common.FMLModContainer.constructMod(FMLModContainer.java:518)
at sun.reflect.GeneratedMethodAccessor2.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at com.google.common.eventbus.EventHandler.handleEvent(EventHandler.java:74)
at com.google.common.eventbus.SynchronizedEventHandler.handleEvent(SynchronizedEventHandler.java:45)
at com.google.common.eventbus.EventBus.dispatch(EventBus.java:313)
at com.google.common.eventbus.EventBus.dispatchQueuedEvents(EventBus.java:296)
at com.google.common.eventbus.EventBus.post(EventBus.java:267)
at cpw.mods.fml.common.LoadController.sendEventToModContainer(LoadController.java:201)
at cpw.mods.fml.common.LoadController.propogateStateMessage(LoadController.java:181)
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 com.google.common.eventbus.EventHandler.handleEvent(EventHandler.java:74)
at com.google.common.eventbus.SynchronizedEventHandler.handleEvent(SynchronizedEventHandler.java:45)
at com.google.common.eventbus.EventBus.dispatch(EventBus.java:313)
at com.google.common.eventbus.EventBus.dispatchQueuedEvents(EventBus.java:296)
at com.google.common.eventbus.EventBus.post(EventBus.java:267)
at cpw.mods.fml.common.LoadController.distributeStateMessage(LoadController.java:112)
at cpw.mods.fml.common.Loader.loadMods(Loader.java:511)
at cpw.mods.fml.server.FMLServerHandler.beginServerLoading(FMLServerHandler.java:99)
at cpw.mods.fml.common.FMLCommonHandler.onServerStart(FMLCommonHandler.java:350)
at net.minecraft.server.dedicated.DedicatedServer.func_71197_b(DedicatedServer.java:92)
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:630)
at net.minecraft.server.ThreadMinecraftServer.run(ThreadMinecraftServer.java:16)
Caused by: java.lang.ClassNotFoundException: scala.collection.Seq
at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:186)
at java.lang.ClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
... 30 more
Caused by: java.lang.NullPointerException
at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:178)
... 32 more

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

-- System Details --
Details:
Minecraft Version: 1.6.4
Operating System: Windows 7 (amd64) version 6.1
Java Version: 1.7.0_55, Oracle Corporation
Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
Memory: 2367777256 bytes (2258 MB) / 3087007744 bytes (2944 MB) up to 3087007744 bytes (2944 MB)
JVM Flags: 2 total; -Xmx3G -Xms3G
AABB Pool Size: 0 (0 bytes; 0 MB) allocated, 0 (0 bytes; 0 MB) used
Suspicious classes: FML and Forge are installed
IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
CraftBukkit Information:
Running:
Failed to handle CraftCrashReport:
java.lang.NullPointerException
at org.bukkit.Bukkit.getName(Bukkit.java:72)
at org.bukkit.craftbukkit.v1_6_R3.CraftCrashReport.call(CraftCrashReport.java:19)
at net.minecraft.crash.CrashReportCategory.func_71500_a(CrashReportCategory.java:106)
at net.minecraft.crash.CrashReport.func_71504_g(CrashReport.java:58)
at net.minecraft.crash.CrashReport.(CrashReport.java:40)
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:689)
at net.minecraft.server.ThreadMinecraftServer.run(ThreadMinecraftServer.java:16)

FML: MCP v8.11 FML v6.4.49.965 Minecraft Forge 9.11.1.965 24 mods loaded, 24 mods active
mcp{8.09} [Minecraft Coder Pack] (minecraft.jar) Unloaded->Constructed
FML{6.4.49.965} [Forge Mod Loader] (Artillery.jar) Unloaded->Constructed
Forge{9.11.1.965} [Minecraft Forge] (Artillery.jar) Unloaded->Constructed
CodeChickenCore{0.9.0.9} [CodeChicken Core] (minecraft.jar) Unloaded->Constructed
bspkrsCore{v5.3(1.6.4)} [bspkrsCore] ([1.6.4]bspkrsCorev5.3.zip) Unloaded->Constructed
TreeCapitator{Forge 1.6.4.r09} [Treecapitator] ([1.6.4]TreeCapitator.Forge.1.6.4.r09.Universal.zip) Unloaded->Constructed
IC2{2.0.397-experimental} [IndustrialCraft 2] (industrialcraft-2_2.0.397-experimental.jar) Unloaded->Constructed
AdvancedMachines{1.0.6} [IC2 Advanced Machines Addon] (AdvancedMachines_exp_1.6.4.zip) Unloaded->Constructed
CompactSolars{4.4.21.306} [Compact Solar Arrays] (compactsolars-universal-1.6.4-4.4.21.306.zip) Unloaded->Constructed
IC2NuclearControl{1.6.2e} [Nuclear Control] (IC2NuclearControl-1.6.2e-ic2-experimental.zip) Unloaded->Constructed
ModularForceFieldSystem{2.5.0} [Modular ForceField System] (MFFS-2.5.0.zip) Unloaded->Constructed
AdvancedSolarPanel{3.4.7} [Advanced Solar Panels] (mod_AdvancedSolarPanels_3_4_7_IC_EXP.zip) Unloaded->Constructed
GraviSuite{1.9.9a} [Gravitation Suite] (mod_zGraviSuite_1_9_9a_MC_1_6_4_IC_EXP.zip) Unloaded->Constructed
ForgeMultipart{1.0.0.244} [Forge Multipart] (ForgeMultipart-universal-1.6.4-1.0.0.244.jar) Unloaded->Constructed
ProjRed|Core{4.3.7.32} [ProjectRed] (ProjectRedBase-1.6.4-4.3.7.32.jar) Unloaded->Constructed
ProjRed|Transmission{4.3.7.32} [ProjectRed-Transmission] (ProjectRedIntegration-1.6.4-4.3.7.32.jar) Unloaded->Constructed
ProjRed|Transportation{4.3.7.32} [ProjectRed-Transportation] (ProjectRedMechanical-BETA-1.6.4-4.3.7.32.jar) Unloaded->Constructed
ProjRed|Exploration{4.3.7.32} [ProjectRed-Exploration] (ProjectRedWorld-1.6.4-4.3.7.32.jar) Unloaded->Constructed
ProjRed|Compatibility{4.3.7.32} [ProjectRed-Compatibility] (ProjectRedCompat-1.6.4-4.3.7.32.jar) Unloaded->Constructed
ProjRed|Integration{4.3.7.32} [ProjectRed-Integration] (ProjectRedIntegration-1.6.4-4.3.7.32.jar) Unloaded->Constructed
ProjRed|Illumination{4.3.7.32} [ProjectRed-Illumination] (ProjectRedLighting-1.6.4-4.3.7.32.jar) Unloaded->Constructed
ProjRed|Expansion{4.3.7.32} [ProjectRed-Expansion] (ProjectRedMechanical-BETA-1.6.4-4.3.7.32.jar) Unloaded->Constructed
McMultipart{1.0.0.244} [Minecraft Multipart Plugin] (ForgeMultipart-universal-1.6.4-1.0.0.244.jar) Unloaded->Constructed
ForgeMicroblock{1.0.0.244} [Forge Microblocks] (ForgeMultipart-universal-1.6.4-1.0.0.244.jar) Unloaded
Profiler Position: N/A (disabled)
Is Modded: Definitely; Server brand changed to 'mcpc,craftbukkit,fml,forge'
Type: Dedicated Server (map_server.txt)

I recommend using the search function
There is a fix for this issue, see #403 (comment) It is an issue with MCPC, but you can fix it yourself.