Server error?

On my server (I assume this to do with forge) whenever I rightclick on certain blocks I get this error:

(Client side error log)

2013-02-12 12:56:44 [iNFO] [sTDERR] java.lang.reflect.InvocationTargetException

2013-02-12 12:56:44 [iNFO] [sTDERR] at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)

2013-02-12 12:56:44 [iNFO] [sTDERR] at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)

2013-02-12 12:56:44 [iNFO] [sTDERR] at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)

2013-02-12 12:56:44 [iNFO] [sTDERR] at java.lang.reflect.Constructor.newInstance(Unknown Source)

2013-02-12 12:56:44 [iNFO] [sTDERR] at codechicken.nei.ItemMobSpawner.getEntity(ItemMobSpawner.java:96)

2013-02-12 12:56:44 [iNFO] [sTDERR] at codechicken.nei.ItemMobSpawner.a(ItemMobSpawner.java:79)

2013-02-12 12:56:44 [iNFO] [sTDERR] at ur.a(SourceFile:388)

2013-02-12 12:56:44 [iNFO] [sTDERR] at codechicken.nei.forge.GuiContainerManager.itemDisplayNameMultiline(GuiContainerManager.java:153)

2013-02-12 12:56:44 [iNFO] [sTDERR] at codechicken.nei.forge.GuiContainerManager.concatenatedDisplayName(GuiContainerManager.java:199)

2013-02-12 12:56:44 [iNFO] [sTDERR] at codechicken.nei.ItemList$ThreadLoadItems.run(ItemList.java:194)

2013-02-12 12:56:44 [iNFO] [sTDERR] Caused by: java.lang.NullPointerException

2013-02-12 12:56:44 [iNFO] [sTDERR] at drzhark.mocreatures.MoCEntityHorseMob.selectType(MoCEntityHorseMob.java:42)

2013-02-12 12:56:44 [iNFO] [sTDERR] at drzhark.mocreatures.MoCEntityMob.<init>(MoCEntityMob.java:34)

2013-02-12 12:56:44 [iNFO] [sTDERR] at drzhark.mocreatures.MoCEntityHorseMob.<init>(MoCEntityHorseMob.java:19)

2013-02-12 12:56:44 [iNFO] [sTDERR] ... 10 more

2013-02-12 12:56:44 [iNFO] [sTDERR] java.lang.reflect.InvocationTargetException

2013-02-12 12:56:44 [iNFO] [sTDERR] at sun.reflect.GeneratedConstructorAccessor57.newInstance(Unknown Source)

2013-02-12 12:56:44 [iNFO] [sTDERR] at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)

2013-02-12 12:56:44 [iNFO] [sTDERR] at java.lang.reflect.Constructor.newInstance(Unknown Source)

2013-02-12 12:56:44 [iNFO] [sTDERR] at codechicken.nei.ItemMobSpawner.getEntity(ItemMobSpawner.java:96)

2013-02-12 12:56:44 [iNFO] [sTDERR] at codechicken.nei.ItemMobSpawner.a(ItemMobSpawner.java:79)

2013-02-12 12:56:44 [iNFO] [sTDERR] at ur.a(SourceFile:388)

2013-02-12 12:56:44 [iNFO] [sTDERR] at codechicken.nei.forge.GuiContainerManager.itemDisplayNameMultiline(GuiContainerManager.java:153)

2013-02-12 12:56:44 [iNFO] [sTDERR] at codechicken.nei.forge.GuiContainerManager.concatenatedDisplayName(GuiContainerManager.java:199)

2013-02-12 12:56:44 [iNFO] [sTDERR] at codechicken.nei.ItemList$ThreadLoadItems.run(ItemList.java:194)

2013-02-12 12:56:44 [iNFO] [sTDERR] Caused by: java.lang.NullPointerException

2013-02-12 12:56:44 [iNFO] [sTDERR] at drzhark.mocreatures.MoCEntityWerewolf.setHumanForm(MoCEntityWerewolf.java:124)

2013-02-12 12:56:44 [iNFO] [sTDERR] at drzhark.mocreatures.MoCEntityWerewolf.<init>(MoCEntityWerewolf.java:29)

2013-02-12 12:56:44 [iNFO] [sTDERR] ... 9 more

2013-02-12 12:56:45 [iNFO] [sTDERR] java.lang.reflect.InvocationTargetException

2013-02-12 12:56:45 [iNFO] [sTDERR] at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)

2013-02-12 12:56:45 [iNFO] [sTDERR] at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)

2013-02-12 12:56:45 [iNFO] [sTDERR] at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)

2013-02-12 12:56:45 [iNFO] [sTDERR] at java.lang.reflect.Constructor.newInstance(Unknown Source)

2013-02-12 12:56:45 [iNFO] [sTDERR] at codechicken.nei.ItemMobSpawner.getEntity(ItemMobSpawner.java:96)

2013-02-12 12:56:45 [iNFO] [sTDERR] at codechicken.nei.ItemMobSpawner.a(ItemMobSpawner.java:79)

2013-02-12 12:56:45 [iNFO] [sTDERR] at ur.a(SourceFile:388)

2013-02-12 12:56:45 [iNFO] [sTDERR] at codechicken.nei.forge.GuiContainerManager.itemDisplayNameMultiline(GuiContainerManager.java:153)

2013-02-12 12:56:45 [iNFO] [sTDERR] at codechicken.nei.forge.GuiContainerManager.concatenatedDisplayName(GuiContainerManager.java:199)

2013-02-12 12:56:45 [iNFO] [sTDERR] at codechicken.nei.ItemList$ItemMatcher.matches(ItemList.java:39)

2013-02-12 12:56:45 [iNFO] [sTDERR] at codechicken.nei.ItemList$ThreadMatchSearch.run(ItemList.java:106)

2013-02-12 12:56:45 [iNFO] [sTDERR] Caused by: java.lang.NullPointerException

2013-02-12 12:56:45 [iNFO] [sTDERR] at drzhark.mocreatures.MoCEntityHorseMob.selectType(MoCEntityHorseMob.java:42)

2013-02-12 12:56:45 [iNFO] [sTDERR] at drzhark.mocreatures.MoCEntityMob.<init>(MoCEntityMob.java:34)

2013-02-12 12:56:45 [iNFO] [sTDERR] at drzhark.mocreatures.MoCEntityHorseMob.<init>(MoCEntityHorseMob.java:19)

2013-02-12 12:56:45 [iNFO] [sTDERR] ... 11 more

(Server side log)

[WARNING] Failed to handle packet for [my username]/[my ip]: java.lang.NullPointerException

java.lang.NullPointerException

at iv.a(NetServerHandler.java:639)

at fk.a(SourceFile:58)

at cg.b(TcpConnection.java:458)

at iv.d(NetServerHandler.java:136)

at iw.b(NetworkListenThread.java:57)

at ht.b(SourceFile:30)

at net.minecraft.server.MinecraftServer.r(MinecraftServer.java:703)

at ho.r(DedicatedServer.java:269)

at net.minecraft.server.MinecraftServer.q(MinecraftServer.java:599)

at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:497)

at fy.run(SourceFile:849)

I'm using the latest version of forge, but I have also noticed this problem with the recommended build.

Also the blocks I have experienced this is with Extra bees indexer and the static database, and a mystcraft book stand.