"Error: Could not find or load main class FTB" when trying to load any modpacks

[thezurxhd]

Hello, whenever I try to play any modpack in ftb it gives me the error message: 'Error: Could not find or load main class FTB". It does this with both exe and jar, I have uninstalled and reinstalled java many times but that has not worked. Any help on why this is doing this would be appreciated. Here is the pastebin if this helps: http://pastebin.com/TpCRQJAB