I was trying to play some Feet-The-Beast with a couple of my friends, launched Direwolf20 and it kept crashing everything I try to launch it. I've tried to reinstall the mod pack, and even my launcher, but nothing has worked.
This is what the log comes out with after a failure in loading.
Spoiler
Logging in...
Beginning authlib authentication attempt
successfully created YggdrasilAuthenticationService
Login complete.
Checking local assets file, for MC version1.7.10 Please wait!
Setting up native libraries for Direwolf20 v 1.4.1 MC 1.7.10
Syncing Assets:
Java Path: C:\Program Files\Java\jre1.8.0_45\bin\javaw.exe
Pack: Direwolf20 1.7.10
Setting MinMemory to 256
Setting MaxMemory to 2048
[18:19:28] [main/INFO]: Loading tweak class name cpw.mods.fml.common.launcher.FMLTweaker
[18:19:28] [main/ERROR]: Unable to launch
java.lang.ClassNotFoundException: cpw.mods.fml.common.launcher.FMLTweaker
at java.net.URLClassLoader.findClass(Unknown Source) ~[?:1.8.0_45]
at java.lang.ClassLoader.loadClass(Unknown Source) ~[?:1.8.0_45]
at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source) ~[?:1.8.0_45]
at java.lang.ClassLoader.loadClass(Unknown Source) ~[?:1.8.0_45]
at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:106) ~[launchwrapper-1.11.jar:?]
at java.lang.ClassLoader.loadClass(Unknown Source) ~[?:1.8.0_45]
at java.lang.ClassLoader.loadClass(Unknown Source) ~[?:1.8.0_45]
at java.lang.Class.forName0(Native Method) ~[?:1.8.0_45]
at java.lang.Class.forName(Unknown Source) ~[?:1.8.0_45]
at net.minecraft.launchwrapper.Launch.launch(Launch.java:98) [launchwrapper-1.11.jar:?]
at net.minecraft.launchwrapper.Launch.main(Launch.java:28) [launchwrapper-1.11.jar:?]
[i18n] Added 0 enUS to options pane
[i18n] Added 1 cyGB to options pane
[i18n] Added 2 daDK to options pane
[i18n] Added 3 deDE to options pane
[i18n] Added 4 enUS to options pane
[i18n] Added 5 enGB to options pane
[i18n] Added 6 esES to options pane
[i18n] Added 7 fiFI to options pane
[i18n] Added 8 frCA to options pane
[i18n] Added 9 frFR to options pane
[i18n] Added 10 itIT to options pane
[i18n] Added 11 nlNL to options pane
[i18n] Added 12 noNO to options pane
[i18n] Added 13 maHU to options pane
[i18n] Added 14 ptBR to options pane
[i18n] Added 15 ptPT to options pane
[i18n] Added 16 ruRU to options pane
[i18n] Added 17 svSE to options pane
[i18n] Added 18 zhCN to options pane
[i18n] enUS English (US) language file loaded!