At first, Forge actually works without any mods in it, but when I started putting together a bunch of mods just to play a custom map, I received the Crash Report saying Spawner GUI isn't compatible to FML at all. Here's the crash report:

 

Guys you know how to fix this crash?

 

---- Minecraft Crash Report ----

// I let you down. Sorry

 

Time: 4/4/13 5:40 PM

Description: Exception in server tick loop

 

java.lang.IllegalAccessError: tried to access class TileEntityMobSpawnerLogicExtended from class net.minecraft.tileentity.TileEntityMobSpawner

at net.minecraft.tileentity.TileEntityMobSpawner.<init>(TileEntityMobSpawner.java:5)

at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)

at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)

at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)

at java.lang.reflect.Constructor.newInstance(Unknown Source)

at java.lang.Class.newInstance0(Unknown Source)

at java.lang.Class.newInstance(Unknown Source)

at net.minecraft.tileentity.TileEntity.func_70317_c(TileEntity.java:137)

at net.minecraft.world.chunk.storage.AnvilChunkLoader.func_75823_a(AnvilChunkLoader.java:432)

at net.minecraft.world.chunk.storage.AnvilChunkLoader.func_75822_a(AnvilChunkLoader.java:103)

at net.minecraft.world.chunk.storage.AnvilChunkLoader.func_75815_a(AnvilChunkLoader.java:83)

at net.minecraft.world.gen.ChunkProviderServer.func_73239_e(ChunkProviderServer.java:182)

at net.minecraft.world.gen.ChunkProviderServer.func_73158_c(ChunkProviderServer.java:118)

at net.minecraft.server.MinecraftServer.func_71222_d(MinecraftServer.java:281)

at net.minecraft.server.integrated.IntegratedServer.func_71247_a(IntegratedServer.java:115)

at net.minecraft.server.integrated.IntegratedServer.func_71197_b(IntegratedServer.java:138)

at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:429)

at net.minecraft.server.ThreadMinecraftServer.run(SourceFile:573)

 

 

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

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

 

-- System Details --

Details:

Minecraft Version: 1.5.1

Operating System: Windows 7 (x86) version 6.1

Java Version: 1.6.0_43, Sun Microsystems Inc.

Java VM Version: Java HotSpot Client VM (mixed mode), Sun Microsystems Inc.

Memory: 372627616 bytes (355 MB) / 519110656 bytes (495 MB) up to 1037959168 bytes (989 MB)

JVM Flags: 2 total; -Xms512m -Xmx1024m

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: 23, tallocated: 41

FML: MCP v7.44 FML v5.1.8.611 Minecraft Forge 7.7.1.611 Optifine OptiFine_1.5.1_HD_U_B1 6 mods loaded, 6 mods active

mcp [Minecraft Coder Pack] (minecraft.jar) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available

FML [Forge Mod Loader] (coremods) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available

Forge [Minecraft Forge] (coremods) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available

mod_SpawnerGUI [mod_SpawnerGUI] (minecraft.jar) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available

mod_TooManyItems [mod_TooManyItems] (minecraft.jar) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available

Pixelmon [Pixelmon] (Pixelmon 2.1.2.zip) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available

Profiler Position: N/A (disabled)

Vec3 Pool Size: 0 (0 bytes; 0 MB) allocated, 0 (0 bytes; 0 MB) used

Player Count: 0 / 8; []

Type: Integrated Server (map_client.txt)

 

Can I use Modloader also along with Forge?

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