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So I downloaded Forge 1.7.10 and I loaded it up with no mods and I keep getting a error that says "It looks like you are using a unsupported modified version of the game".

Here's the crash report.

---- Minecraft Crash Report -------- Minecraft Crash Report ----// There are four lights!
Time: 6/8/17 7:54 PMDescription: Initializing game
java.lang.NoClassDefFoundError: bna at java.lang.Class.getDeclaredFields0(Native Method) at java.lang.Class.privateGetDeclaredFields(Class.java:2575) at java.lang.Class.getField0(Class.java:2967) at java.lang.Class.getField(Class.java:1693) at cpw.mods.fml.client.FMLClientHandler.detectOptifine(FMLClientHandler.java:277) at cpw.mods.fml.client.FMLClientHandler.beginMinecraftLoading(FMLClientHandler.java:192) at net.minecraft.client.Minecraft.func_71384_a(Minecraft.java:480) at net.minecraft.client.Minecraft.func_99999_d(Minecraft.java:878) at net.minecraft.client.main.Main.main(SourceFile:148) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:483) at net.minecraft.launchwrapper.Launch.launch(Launch.java:135) at net.minecraft.launchwrapper.Launch.main(Launch.java:28)Caused by: java.lang.ClassNotFoundException: bna at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:191) at java.lang.ClassLoader.loadClass(ClassLoader.java:424) at java.lang.ClassLoader.loadClass(ClassLoader.java:357) ... 15 moreCaused by: java.lang.NullPointerException at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:182) ... 17 more

A detailed walkthrough of the error, its code path and all known details is as follows:---------------------------------------------------------------------------------------
-- Head --Stacktrace: at java.lang.Class.getDeclaredFields0(Native Method) at java.lang.Class.privateGetDeclaredFields(Class.java:2575) at java.lang.Class.getField0(Class.java:2967) at java.lang.Class.getField(Class.java:1693) at cpw.mods.fml.client.FMLClientHandler.detectOptifine(FMLClientHandler.java:277) at cpw.mods.fml.client.FMLClientHandler.beginMinecraftLoading(FMLClientHandler.java:192) at net.minecraft.client.Minecraft.func_71384_a(Minecraft.java:480)
-- Initialization --Details:Stacktrace: at net.minecraft.client.Minecraft.func_99999_d(Minecraft.java:878) at net.minecraft.client.main.Main.main(SourceFile:148) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:483) 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 8.1 (amd64) version 6.3 Java Version: 1.8.0_25, Oracle Corporation Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation Memory: 97053960 bytes (92 MB) / 198455296 bytes (189 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: Launched Version: 1.7.10-Forge10.13.4.1558-1.7.10 LWJGL: 2.9.1 OpenGL: GeForce GTX 760/PCIe/SSE2 GL version 4.5.0 NVIDIA 376.33, 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.Shader