strange java error/warning message

[tiger2000]

Dear all,

could someone advise how to track where's this from?

2010-01-06 18:15:23,252 ERROR [btpool0-98] [] log - handle failed
java.lang.IllegalStateException: response
        at org.mortbay.jetty.HttpConnection$RequestHandler.startResponse(HttpConnection.java:855)
        at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:403)
        at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:205)
        at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:364)
        at org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:396)        at org.mortbay.thread.BoundedThreadPool$PoolThread.run(BoundedThreadPool.java:442)

Thanks.