Minecraft crashing upon connecting to my server.

[Java_SE_Binary]

Alright so, I have modified Resonant Rise 3 so that it has 25 extra mods and I've gone through, fixed id conflicts etc etc. But now I've come upon a new... I'll call it a 'feature' I guess, where players crash upon trying to connect to a server. Unless they load a single player world first, then connect. Otherwise Minecraft throws a ticking screen error, seen here: http://pastebin.com/Ux2dncAD

[jeffryfisher]

It looks as if you have multiple core mods. Forge does not work well with some core mods, and you'll have trouble finding help here sorting out the conflicts. If you are coding a mod, please create a separate test world in which it is the only mod, and then show us the crash.