Running specjbb on linux-x86 as part of a jprt job running fastdebug:

=============== DEBUG MESSAGE: corrupted control word detected
 ================

# To suppress the following error report, specify this argument
# after -XX: or in .hotspotrc:  SuppressErrorAt=/assembler_x86.cpp:4920
#
# A fatal error has been detected by the Java Runtime Environment:
#
#  Internal Error (/tmp/jprt/P1/B/183229.kk1971/source/src/cpu/x86/vm/assembler_x86.cpp:4920),
 pid=650, tid=3027954592
#  Error: assert(false,"DEBUG MESSAGE")
#
# JRE version: 7.0-b52
# Java VM: OpenJDK Client VM
 (15.0-b04-2009-04-02-183229.kk1971.dolphinfixeshg-fastdebug mixed mode,
 sharing linux-x86 )

Error log is attached
A recent build of hotspot with MVM support also ran into this intermittent
problem.  The JPRT test run is at...

http://j2se.east.sun.com/net/prt-data.east.sun.com/archives/jprt/2009/10/2009-10-15-033803.jmelvin.hotspot/logs/linux_i586-fastdebug-c1-jbb_default.log

Failing commandline is...

/tmp/jprt/P1/T/033803.jmelvin/testproduct/linux_i586_2.6-fastdebug/bin/java -client -Xmx384M -XX:+PrintGC spec.jbb.JBBmain -propfile SPECjbb.props

NOTE: Likely a build on RedHat and test on Suse Linux.  Not sure this is material.
Also the test 
com/sun/jdi/TwoThreadsTest.java 
fails with same reason. Here is the jtr:
http://sqeweb.sfbay.sun.com/nfs/results/vm/gtee/HSX/PIT/VM/16/b13/jdk6u18b06/fastdebug/javase/linux-i586/server/mixed/linux-i586_server_mixed_JDI_REGRESSION/workDir/com/sun/jdi/TwoThreadsTest.jtr

Versions are:
HSX 16 b13
JDK 6u18b06
The OS: Red Hat Enterprise Linux Server release 5.4 (Tikanga)
It seems that runThese fails with the same message on the linux-i586.
http://sqeweb.sfbay.sun.com/nfs/tools/gtee/results/19/b05/jdk7b104/fastdebug/bigapps/linux-i586/server/mixed/linux-i586_bigapps_server_mixed_runThese/runThese//hs_err_pid31609.log
;; Using jvm: "/export/local/common/jdk/baseline/linux-i586/jre/lib/i386/server/libjvm.so"
#
# A fatal error has been detected by the Java Runtime Environment:
#
#  Internal Error (/tmp/jprt/P1/B/061816.et151817/source/src/cpu/x86/vm/assembler_x86.cpp:5013), pid=31609, tid=2553031568
#  assert(false) failed: DEBUG MESSAGE
#
# JRE version: 7.0
# Java VM: Java HotSpot(TM) Server VM (19.0-b05-201007300618.et151817.hs19b05-fastdebug mixed mode linux-x86 )
# If you would like to submit a bug report, please visit:
#   http://java.sun.com/webapps/bugreport/crash.jsp
#

---------------  T H R E A D  ---------------

Current thread (0x09764000):  JavaThread "AWT-EventQueue-0" [_thread_in_vm, id=3480, stack(0x98272000,0x982c3000)]

Stack: [0x98272000,0x982c3000],  sp=0x982c1b30,  free space=13e982c1b90k
Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
V  [libjvm.so+0xa2a6e7];;  _ZN7VMError6reportEP12outputStream+0x1207
V  [libjvm.so+0xa2a96b];;  _ZN7VMError14report_and_dieEv+0x18b
V  [libjvm.so+0x4a6dc8];;  _Z15report_vm_errorPKciS0_S0_+0x68
V  [libjvm.so+0x257d98];;  _ZN14MacroAssembler7debug32EiiiiiiiiiPc+0x258
v  ~RuntimeStub::resolve_opt_virtual_call