Cannot create new worlds, or play existing ones.

[SneakyPete]

Any time I try to create, or play an existing ssp world, my game just crashes. Although I can play smp just fine without issue.

FTB Launcher version: v1.2.4
Minecraft Version: 1.4.7
Java version: 1.7.0_21
Error logs: http://pastebin.com/aQwFDjg8

Pretty sure this is the issue, Although I don't know what it means

2013-05-20 01:16:21 [SEVERE] [ForgeModLoader] The ForgeModLoader state engine has become corrupted. Probably, a state was missed by and invalid modification to a base classForgeModLoader depends on. This is a critical error and not recoverable. Investigate any modifications to base classes outside ofForgeModLoader, especially Optifine, to see if there are fixes available.
2013-05-20 01:16:21 [INFO] [STDERR] Exception in thread "Server thread" java.lang.RuntimeException: The ForgeModLoader state engine is invalid
2013-05-20 01:16:21 [INFO] [STDERR] at cpw.mods.fml.common.LoadController.transition(LoadController.java:122)
2013-05-20 01:16:21 [INFO] [STDERR] at cpw.mods.fml.common.Loader.serverStopped(Loader.java:780)
2013-05-20 01:16:21 [INFO] [STDERR] at cpw.mods.fml.common.FMLCommonHandler.handleServerStopped(FMLCommonHandler.java:469)
2013-05-20 01:16:21 [INFO] [STDERR] at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:559)
2013-05-20 01:16:21 [INFO] [STDERR] at fy.run(SourceFile:849)

 

[Moasseman]

Delete all FTB related stuffs (you can backup your world) and then download it again from feed-the-beast.com

 

[Ashzification]

Please follow these steps exactly: http://desk.feed-the-beast.com/index.php?/Knowledgebase/Article/View/9/0/basic-troubleshooting
This is to rule out any issues with your client setup.


If the troubleshooting doesn't work, please upload your launchers console log to pastebin.com and link the paste here.

 

[Eyamaz]

Did you add any additional mods?

Please go to your options tab in the launcher and click the force update button and relaunch your modpack and start a new world without adding any other mods.