It looks like you have some mods that are missing functions with the title of main. All of your mods should have one function with the title of main (lowercase main) otherwise the mods won't run and can sometimes cause server connection problems in general, when connecting to our minecraft server. This is because 'main' is the signal that tells our software to begin running the mod.
We've fixed one or two mods already, and we'll check for more, then we'll download a new world to reset it in case there's anything else. You can always go back to your old world, by clicking 'my stuff < worlds'