I have this weird problem. Already asked it on the minecraft forums, but I think it might be problem with forge, cause it actually affects few different mods (ICMB, UE and buildcraft). Here's the quote from minecraftforums.net:
I've posted this in Calclavia's ICMB topic and he said that's a really weird error and there might be a problem with Java. Reinstalling it didn't help though. Also, tried running without Optifine and still nothing.
I was thinking that it might be a problem with some forge files, where it saves mod data or something? Maybe those files got corrupted when my PC crashed. Don't know how to fix it anyway. I hope someone can help, cause I've literally spent three hours trying to fix this