With -XX:-UseBiasedLocking Queens runs.
jvmg build on x86 solaris.
I was using -XX:-UseFastLocking to try to debug some other problem, not sure if you can produce this otherwise.

% gamma -Xcomp -XX:-UseFastLocking Queens
VM option '-UseFastLocking'
# To suppress the following error report, specify this argument
# after -XX: or in .hotspotrc: SuppressErrorAt=/synchronizer.cpp:3440
#
# A fatal error has been detected by the Java Runtime Environment:
#
# Internal Error (/net/philli/scratch1/coleenp/hg/6859079/src/share/vm/runtime/synchronizer.cpp:3440), pid=4226, tid=1
# Error: assert(false,"Non-balanced monitor enter/exit!")
#
# JRE version: 7.0-b45
# Java VM: Java HotSpot(TM) Client VM (16.0-b04-6859079_0720_1530-jvmg compiled mode solaris-x86 )
# An error report file with more information is saved as:
# /net/philli/scratch1/coleenp/hg/6859079/make/solaris/solaris_i486_compiler1/jvmg/hs_err_pid4226.log
#
# If you would like to submit a bug report, please visit:
# http://java.sun.com/webapps/bugreport/crash.jsp
#
Current thread is 1
Dumping core ...
Abort
ruger%

hs_err file attached.