source sequence is illegal/malformed utf-8

gistfile1.txt

["Received new event", {:source=>"tcp://0.0.0.0:1556/client/127.0.0.1:38974", :event=>#<LogStash::Event:0x3b215c11 @data={"@source"=>"tcp://0.0.0.0:1556/client/127.0.0.1:38974", "@type"=>"akamai", "@tags"=>[], "@fields"=>{}, "@timestamp"=>"2012-10-02T17:50:51.812000Z", "@source_host"=>"0.0.0.0", "@source_path"=>"/client/127.0.0.1:38974", "@message"=>"12.53.117.198 - - [26/Sep/2012:23:22:52 +0000] \"GET /www.weather.com/ HTTP/1.1\" 200 96556 \"-\" \"Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.1 (KHTML, like Gecko) Chrome/21.0.1180.89 Safari/537.1\" \"-\"\n"}, @cancelled=false>}] {"level":"debug","file":"/opt/logstash/logstash-1.1.1-monolithic.jar!/logstash/inputs/base.rb","line":"129","method":"to_event"}
JSON::GeneratorError: source sequence is illegal/malformed utf-8
          to_json at json/ext/GeneratorMethods.java:71
          to_json at file:/opt/logstash/logstash-1.1.1-monolithic.jar!/logstash/event.rb:132
          to_json at json/ext/GeneratorMethods.java:71
        tty_write at file:/opt/logstash/logstash-1.1.1-monolithic.jar!/gems/cabin-0.4.4/lib/cabin/outputs/io.rb:80
               << at file:/opt/logstash/logstash-1.1.1-monolithic.jar!/gems/cabin-0.4.4/lib/cabin/outputs/io.rb:55
               << at file:/opt/logstash/logstash-1.1.1-monolithic.jar!/gems/cabin-0.4.4/lib/cabin/outputs/io.rb:51
          publish at file:/opt/logstash/logstash-1.1.1-monolithic.jar!/gems/cabin-0.4.4/lib/cabin/channel.rb:171
             each at org/jruby/RubyHash.java:1186
          publish at file:/opt/logstash/logstash-1.1.1-monolithic.jar!/gems/cabin-0.4.4/lib/cabin/channel.rb:170
          publish at file:/opt/logstash/logstash-1.1.1-monolithic.jar!/gems/cabin-0.4.4/lib/cabin/channel.rb:169
             _log at file:/opt/logstash/logstash-1.1.1-monolithic.jar!/gems/cabin-0.4.4/lib/cabin/mixins/logger.rb:102
   log_with_level at file:/opt/logstash/logstash-1.1.1-monolithic.jar!/gems/cabin-0.4.4/lib/cabin/mixins/logger.rb:79
             warn at file:/opt/logstash/logstash-1.1.1-monolithic.jar!/gems/cabin-0.4.4/lib/cabin/mixins/logger.rb:64
           filter at file:/opt/logstash/logstash-1.1.1-monolithic.jar!/logstash/filterworker.rb:62
           filter at file:/opt/logstash/logstash-1.1.1-monolithic.jar!/logstash/filterworker.rb:58
           filter at file:/opt/logstash/logstash-1.1.1-monolithic.jar!/logstash/filterworker.rb:56
             each at org/jruby/RubyArray.java:1615
           filter at file:/opt/logstash/logstash-1.1.1-monolithic.jar!/logstash/filterworker.rb:48
             each at org/jruby/RubyArray.java:1615
           filter at file:/opt/logstash/logstash-1.1.1-monolithic.jar!/logstash/filterworker.rb:47
              run at file:/opt/logstash/logstash-1.1.1-monolithic.jar!/logstash/filterworker.rb:32
       run_filter at file:/opt/logstash/logstash-1.1.1-monolithic.jar!/logstash/agent.rb:708
  run_with_config at file:/opt/logstash/logstash-1.1.1-monolithic.jar!/logstash/agent.rb:435
Exception in thread "LogStash::Runner" org.jruby.exceptions.RaiseException: (SystemExit) source sequence is illegal/malformed utf-8
	at org.jruby.RubyThread.join(org/jruby/RubyThread.java:509)
	at Agent.wait(file:/opt/logstash/logstash-1.1.1-monolithic.jar!/logstash/agent.rb:326)
	at logstash.runner.main(logstash/runner.rb:42)
	at org.jruby.RubyArray.each(org/jruby/RubyArray.java:1615)
	at logstash.runner.main(logstash/runner.rb:41)
	at logstash.runner.(root)(logstash/runner.rb:120)