I encountered the attached error report when debugging an instance of netbeans with another instance of netbeans. 

java version "1.4.1"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.1-b21)
Java HotSpot(TM) Client VM (build 1.4.1-b21, mixed mode)


Unexpected Signal : 11 occurred at PC=0xFECE8FA4
Function=[Unknown. Nearest: JVM_MonitorWait+0x251C]
Library=/usr/j2se/jre/lib/sparc/client/libjvm.so

Current Java thread:

Dynamic libraries:
0x10000         /usr/j2se/bin/java
0xff370000      /usr/lib/libthread.so.1
0xff3a0000      /usr/lib/libdl.so.1
0xff280000      /usr/lib/libc.so.1
0xff360000      /usr/platform/SUNW,Sun-Blade-1000/lib/libc_psr.so.1
0xfec00000      /usr/j2se/jre/lib/sparc/client/libjvm.so
0xff240000      /usr/lib/libCrun.so.1
0xff210000      /usr/lib/libsocket.so.1
0xff100000      /usr/lib/libnsl.so.1
0xff1e0000      /usr/lib/libm.so.1
0xff270000      /usr/lib/libw.so.1
0xff0e0000      /usr/lib/libmp.so.2
0xff0c0000      /usr/lib/librt.so.1
0xff0a0000      /usr/lib/libaio.so.1
0xff080000      /usr/lib/libmd5.so.1
0xff050000      /usr/platform/SUNW,Sun-Blade-1000/lib/libmd5_psr.so.1
0xfebd0000      /usr/j2se/jre/lib/sparc/native_threads/libhpi.so
0xfeba0000      /usr/j2se/jre/lib/sparc/libverify.so
0xfeb50000      /usr/j2se/jre/lib/sparc/libjava.so
0xfeb30000      /usr/j2se/jre/lib/sparc/libzip.so
0xfd040000      /usr/j2se/jre/lib/sparc/libjdwp.so
0xfd020000      /usr/j2se/jre/lib/sparc/libdt_socket.so
0xfafe0000      /usr/lib/nss_nis.so.1
0xef100000      /usr/j2se/jre/lib/sparc/libawt.so
0xef900000      /usr/j2se/jre/lib/sparc/libmlib_image.so
0xf0890000      /usr/j2se/jre/lib/sparc/motif21/libmawt.so
0xeee80000      /usr/dt/lib/libXm.so.4
0xf0790000      /usr/openwin/lib/libXt.so.4
0xf0990000      /usr/openwin/lib/libXext.so.0
0xf06e0000      /usr/openwin/lib/libXtst.so.1
0xeed80000      /usr/openwin/lib/libX11.so.4
0xf05a0000      /usr/openwin/lib/libdps.so.5
0xf06c0000      /usr/openwin/lib/libSM.so.6
0xf04d0000      /usr/openwin/lib/libICE.so.6
0xeec80000      /usr/j2se/jre/lib/sparc/libfontmanager.so
0xf04b0000      /usr/lib//liblayout.so
0xe98e0000      /usr/j2se/jre/lib/sparc/libcmm.so
0xe9890000      /usr/j2se/jre/lib/sparc/libjpeg.so

Local Time = Tue Feb 25 16:25:53 2003
Elapsed Time = 1196
#
# HotSpot Virtual Machine Error : 11
# Error ID : 4F530E43505002E6 01
# Please report this error at
# http://java.sun.com/cgi-bin/bugreport.cgi
#
# Java VM: Java HotSpot(TM) Client VM (1.4.1-b21 mixed mode)
#