I don't crash with the new 1.4.6 version, but I do see this buried in the log:
2012-12-23 10:00:31 [INFO] [STDOUT] LiquidUU: Loading Forestry integration...
2012-12-23 10:00:31 [INFO] [STDOUT] LiquidUU: Did not load Forestry integration: java.lang.ClassNotFoundException: ro.narc.liquiduu.integration.Forestry
2012-12-23 10:00:31 [INFO] [STDERR] java.lang.ClassNotFoundException: ro.narc.liquiduu.integration.Forestry
2012-12-23 10:00:31 [INFO] [STDERR] at cpw.mods.fml.relauncher.RelaunchClassLoader.findClass(RelaunchClassLoader.java:179)
2012-12-23 10:00:31 [INFO] [STDERR] at java.lang.ClassLoader.loadClass(Unknown Source)
2012-12-23 10:00:31 [INFO] [STDERR] at java.lang.ClassLoader.loadClass(Unknown Source)
2012-12-23 10:00:31 [INFO] [STDERR] at ro.narc.liquiduu.LiquidUU.loadIntegration(LiquidUU.java:189)
2012-12-23 10:00:31 [INFO] [STDERR] at ro.narc.liquiduu.LiquidUU.postInit(LiquidUU.java:129)
2012-12-23 10:00:31 [INFO] [STDERR] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
2012-12-23 10:00:31 [INFO] [STDERR] at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
2012-12-23 10:00:31 [INFO] [STDERR] at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
2012-12-23 10:00:31 [INFO] [STDERR] at java.lang.reflect.Method.invoke(Unknown Source)
2012-12-23 10:00:31 [INFO] [STDERR] at cpw.mods.fml.common.FMLModContainer.handleModStateEvent(FMLModContainer.java:478)
2012-12-23 10:00:31 [INFO] [STDERR] at sun.reflect.GeneratedMethodAccessor3.invoke(Unknown Source)
2012-12-23 10:00:31 [INFO] [STDERR] at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
2012-12-23 10:00:31 [INFO] [STDERR] at java.lang.reflect.Method.invoke(Unknown Source)
2012-12-23 10:00:31 [INFO] [STDERR] at com.google.common.eventbus.EventHandler.handleEvent(EventHandler.java:69)
2012-12-23 10:00:31 [INFO] [STDERR] at com.google.common.eventbus.SynchronizedEventHandler.handleEvent(SynchronizedEventHandler.java:45)
2012-12-23 10:00:31 [INFO] [STDERR] at com.google.common.eventbus.EventBus.dispatch(EventBus.java:317)
2012-12-23 10:00:31 [INFO] [STDERR] at com.google.common.eventbus.EventBus.dispatchQueuedEvents(EventBus.java:300)
2012-12-23 10:00:31 [INFO] [STDERR] at com.google.common.eventbus.EventBus.post(EventBus.java:268)
2012-12-23 10:00:31 [INFO] [STDERR] at cpw.mods.fml.common.LoadController.propogateStateMessage(LoadController.java:140)
2012-12-23 10:00:31 [INFO] [STDERR] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
2012-12-23 10:00:31 [INFO] [STDERR] at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
2012-12-23 10:00:31 [INFO] [STDERR] at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
2012-12-23 10:00:31 [INFO] [STDERR] at java.lang.reflect.Method.invoke(Unknown Source)
2012-12-23 10:00:31 [INFO] [STDERR] at com.google.common.eventbus.EventHandler.handleEvent(EventHandler.java:69)
2012-12-23 10:00:31 [INFO] [STDERR] at com.google.common.eventbus.SynchronizedEventHandler.handleEvent(SynchronizedEventHandler.java:45)
2012-12-23 10:00:31 [INFO] [STDERR] at com.google.common.eventbus.EventBus.dispatch(EventBus.java:317)
2012-12-23 10:00:31 [INFO] [STDERR] at com.google.common.eventbus.EventBus.dispatchQueuedEvents(EventBus.java:300)
2012-12-23 10:00:31 [INFO] [STDERR] at com.google.common.eventbus.EventBus.post(EventBus.java:268)
2012-12-23 10:00:31 [INFO] [STDERR] at cpw.mods.fml.common.LoadController.distributeStateMessage(LoadController.java:83)
2012-12-23 10:00:31 [INFO] [STDERR] at cpw.mods.fml.common.Loader.initializeMods(Loader.java:659)
2012-12-23 10:00:31 [INFO] [STDERR] at cpw.mods.fml.client.FMLClientHandler.finishMinecraftLoading(FMLClientHandler.java:207)
2012-12-23 10:00:31 [INFO] [STDERR] at net.minecraft.client.Minecraft.a(Minecraft.java:456)
2012-12-23 10:00:31 [INFO] [STDERR] at asq.a(SourceFile:56)
2012-12-23 10:00:31 [INFO] [STDERR] at net.minecraft.client.Minecraft.run(Minecraft.java:744)
2012-12-23 10:00:31 [INFO] [STDERR] at java.lang.Thread.run(Unknown Source)
2012-12-23 10:00:31 [INFO] [STDERR] Caused by: java.lang.NullPointerException
2012-12-23 10:00:31 [INFO] [STDERR] at org.objectweb.asm.ClassReader.<init>(Unknown Source)
2012-12-23 10:00:31 [INFO] [STDERR] at net.minecraftforge.transformers.EventTransformer.transform(EventTransformer.java:29)
2012-12-23 10:00:31 [INFO] [STDERR] at cpw.mods.fml.relauncher.RelaunchClassLoader.runTransformers(RelaunchClassLoader.java:222)
2012-12-23 10:00:31 [INFO] [STDERR] at cpw.mods.fml.relauncher.RelaunchClassLoader.findClass(RelaunchClassLoader.java:171)
2012-12-23 10:00:31 [INFO] [STDERR] ... 34 more