This bug can be reproduced 3/1, 3 time I try I could reproduce once.
Version String:
---------------
java version "1.4.0-beta"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.0-beta-b46)
Java HotSpot(TM) Client VM (build product+1.4+c1_baseline+compiler1+20010109-150942-debug, compiled mode)

Platform:
---------
Solaris sparc, OS 5.8

How to reproduce:
-----------------
ksh /net/sqesvr/export/vsn/VM/merlin/nightly/results/01-09-01/c1_baseline/TONGA/solsparc/results/threads/ResultDir/CancellableThreadTest/CancellableThreadTest.tlog

Output:
-------
#
# HotSpot Virtual Machine Error, assertion failure
# Please report this error at
# http://java.sun.com/cgi-bin/bugreport.cgi
#
# assert(Universe::is_heap(obj), "sanity check")
#
# Error ID: /net/jano/export/disk05/hotspot/auto/ws_jano/fpt/src/share/vm/runtime/handles.cpp, 28 [ Patched ]
#
# Problematic Thread: prio=5 tid=0x745c10 nid=0x4d0 runnable
#
Dumping core....