Steps to reproduce:
1. Start debug for servlet.
2. Quikly press reload in browser 10-15 times.

Result:
IllegalStateException occured, tomcta crashed, following 
output to host_name:11555 tab (output for W2k):

java.lang.IllegalStateException: Current state = FLUSHED, 
new state = CODING_END
        at 
java.nio.charset.CharsetEncoder.throwIllegalStateException
(CharsetEncoder.java:933)
        at java.nio.charset.CharsetEncoder.encode
(CharsetEncoder.java:529)
        at 
sun.nio.cs.StreamEncoder$CharsetSE.flushLeftoverChar
(StreamEncoder.java:356)
        at sun.nio.cs.StreamEncoder$CharsetSE.implClose
(StreamEncoder.java:413)
        at sun.nio.cs.StreamEncoder.close
(StreamEncoder.java:158)
        at java.io.OutputStreamWriter.close
(OutputStreamWriter.java:222)
        at java.io.PrintWriter.close(PrintWriter.java:137)
        at 
org.apache.catalina.connector.ResponseBase.finishResponse
(ResponseBase.java:482)
        at 
org.apache.catalina.connector.HttpResponseBase.finishRespon
se(HttpResponseBase.java:229)
        at 
org.apache.catalina.connector.http.HttpResponseImpl.finishR
esponse(HttpResponseImpl.java:288)
        at 
org.apache.catalina.connector.http.HttpProcessor.process
(HttpProcessor.java:1038)
        at 
org.apache.catalina.connector.http.HttpProcessor.run
(HttpProcessor.java:1106)
        at java.lang.Thread.run(Thread.java:536)
#
# HotSpot Virtual Machine Error, Internal Error
# Please report this error at
# http://java.sun.com/cgi-bin/bugreport.cgi
#
# Java VM: Java HotSpot(TM) Client VM (1.4.0-b92 mixed 
mode)
#
# Error ID: 5052455345525645255843455054494F4E0E435050001B
#
# Problematic Thread: prio=5 tid=0x0F26EDB8 nid=0x4e8 
runnable 
#


Well reproduced with under RH Linux 7.2 & W2K with Sun One 
Studio 4 update 1 (build 020812).