Can't launch any newly downloaded modpacks.

[Verarticus]

Just get this in the console every time.

Logging in...
Login complete.
Horizons
Modpack is up to date.
dirs mk'd
debug: retaining modpack file: C:\Users\David\AppData\Roaming\ftblauncher\ModPacks\Horizons\Horizons.zip
Syncing Assets:
The FTB Launcher has found the following Java versions installed:
The FTB Launcher has found the following Java versions installed:
Java Path: C:\Program Files\Java\jre7\bin\javaw.exe
Setting MinMemory to 256
Setting MaxMemory to 2048
Dec 24, 2013 9:26:26 PM net.minecraft.launchwrapper.LogWrapper log
INFO: Loading tweak class name cpw.mods.fml.common.launcher.FMLTweaker
Dec 24, 2013 9:26:26 PM net.minecraft.launchwrapper.LogWrapper log
INFO: Using primary tweak class name cpw.mods.fml.common.launcher.FMLTweaker
Dec 24, 2013 9:26:26 PM net.minecraft.launchwrapper.LogWrapper log
INFO: Calling tweak class cpw.mods.fml.common.launcher.FMLTweaker
Exception in thread "main" java.lang.NoClassDefFoundError: com/google/common/collect/Lists
at cpw.mods.fml.common.launcher.FMLTweaker.acceptOptions(FMLTweaker.java:52)
at net.minecraft.launchwrapper.Launch.launch(Launch.java:110)
at net.minecraft.launchwrapper.Launch.main(Launch.java:27)
Caused by: java.lang.ClassNotFoundException: com.google.common.collect.Lists
at java.net.URLClassLoader$1.run(Unknown Source)
at java.net.URLClassLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
... 3 more

I've tried reinstalling java, making sure I only have the 64 bit version, reinstalling the pack. Every time I just get that and nothing.

 

[Ancient1992]

This works for me:
Open FTBlauncher,
Push on edit mod pack
Than push on Open Folder
Than you come in the mod folder from jour pack
Ten you push on the Temp folder(in the hot bar above)
The map that is selected you delete it en than run the launcher .

sorry for my spelling, but my native language is not English and hopefully it works for your

 

[venom0213]

This works for me:
Open FTBlauncher,
Push on edit mod pack
Than push on Open Folder
Than you come in the mod folder from jour pack
Ten you push on the Temp folder(in the hot bar above)
The map that is selected you delete it en than run the launcher .

sorry for my spelling, but my native language is not English and hopefully it works for your

What do you mean by push on the temp folder?

 

[vtouraev]

I've had the very same problem. Hopefully someone can answer how to fix this.