Absolutely bizarre error when compiling

[AbeJ]

I'm writing my mod in Scala, and I suddenly started getting these errors when compiling:

 

== Recompiling client ==
> Cleaning bin
> Recompiling
'"scalac" -encoding UTF-8 -deprecation -target:jvm-1.6 -classpath "lib:lib/*:jars/bin/minecraft.jar:j...' failed : 1

== ERRORS FOUND in SCALA CODE ==

src/minecraft/cpw/mods/fml/common/IFMLSidedHandler.java:29: error: value EntityRegistration is not a member of object cpw.mods.fml.common.registry.EntityRegistry
import cpw.mods.fml.common.registry.EntityRegistry.EntityRegistration;
       ^

src/minecraft/cpw/mods/fml/common/IFMLSidedHandler.java:42: error: not found: type EntityRegistration
    Entity spawnEntityIntoClientWorld(EntityRegistration registration, EntitySpawnPacket packet);
                                      ^

 

I don't edit those classes, and I haven't restarted my computer or anything. That problem just started happening when I compiled one time, and now it won't go away. What can I do? I'm using Scala 2.10.0 (not sure if 2.10.1 is compatible).