Had a similar error on a server designed for testing, I used MC edit to copy the valued creations to a new world.
Good luck with your worlds!
Error:
2011-10-24 19:01:28 [SEVERE] Unexpected exception
java.lang.NullPointerException
at en.c(SourceFile:72)
at eh.a(SourceFile:2124)
at jf.d(SourceFile:572)
at ja.c(SourceFile:67)
at ja.b(SourceFile:81)
at eh.c(SourceFile:319)
at eh.a(SourceFile:276)
at eh.f(SourceFile:280)
at eh.a(SourceFile:217)
at st.a(SourceFile:50)
at eh.c(SourceFile:189)
at eh.<init>(SourceFile:150)
at en.<init>(SourceFile:25)
at net.minecraft.server.MinecraftServer.a(SourceFile:195)
at net.minecraft.server.MinecraftServer.c(SourceFile:150)
at net.minecraft.server.MinecraftServer.run(SourceFile:279)
at ce.run(SourceFile:417)
0
Good luck with your worlds!
Error:
2011-10-24 19:01:28 [SEVERE] Unexpected exception
java.lang.NullPointerException
at en.c(SourceFile:72)
at eh.a(SourceFile:2124)
at jf.d(SourceFile:572)
at ja.c(SourceFile:67)
at ja.b(SourceFile:81)
at eh.c(SourceFile:319)
at eh.a(SourceFile:276)
at eh.f(SourceFile:280)
at eh.a(SourceFile:217)
at st.a(SourceFile:50)
at eh.c(SourceFile:189)
at eh.<init>(SourceFile:150)
at en.<init>(SourceFile:25)
at net.minecraft.server.MinecraftServer.a(SourceFile:195)
at net.minecraft.server.MinecraftServer.c(SourceFile:150)
at net.minecraft.server.MinecraftServer.run(SourceFile:279)
at ce.run(SourceFile:417)