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:
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-- 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?