I have pretty much the same problem MinecraftDiamonds was having, except I tried copying and pasting the config files. I even searched each config file for some of the IDs mentioned that are supposedly missmatched, and they were no where to be found in my server or my client.
same with me. and I'm the one making the server. they're all the same mods and it's not saying missmatch just missing. I've copied every config file and even looked to see if I could just change them. but they aren't in there