with perm gen collection enabled,  customer  client crashed after 112 iterations
with tiger b60.
Flags used: -server -XX:+UseConcMarkSweepGC -XX:+PrintGCDetails  -XX:+CMSClassUnloadingEnabled -XX:+CMSPermGenSweepingEnabled

The first error happened in SweepClosure::doGarbageChunk()

Thread 5 (Thread 3076 (LWP 1473)):
#0  0x400d9771 in nanosleep () from /lib/i686/libc.so.6
#1  0x400d9639 in sleep () from /lib/i686/libc.so.6
#2  0x4053c46c in os::message_box(char const*, char const*) ()
   from /usr/j2se/jre/lib/i386/server/libjvm.so
#3  0x40602836 in VMError::show_message_box(char*, int) ()
   from /usr/j2se/jre/lib/i386/server/libjvm.so
#4  0x406024fa in VMError::report_and_die() ()
   from /usr/j2se/jre/lib/i386/server/libjvm.so
#5  0x4053da96 in JVM_handle_linux_signal ()
   from /usr/j2se/jre/lib/i386/server/libjvm.so
#6  0x4053b2c4 in signalHandler(int, siginfo*, void*) ()
   from /usr/j2se/jre/lib/i386/server/libjvm.so
#7  0x4002cb03 in pthread_sighandler_rt () from /lib/i686/libpthread.so.0
#8  <signal handler called>
#9  0x40307ba1 in SweepClosure::doGarbageChunk(FreeChunk*) ()
   from /usr/j2se/jre/lib/i386/server/libjvm.so
#10 0x40307a39 in SweepClosure::do_blk_careful(HeapWord*) ()
   from /usr/j2se/jre/lib/i386/server/libjvm.so
#11 0x402e43bc in CompactibleFreeListSpace::blk_iterate_careful(BlkClosureCareful*) () from /usr/j2se/jre/lib/i386/server/libjvm.so
#12 0x4030460d in CMSCollector::sweep(int) ()
   from /usr/j2se/jre/lib/i386/server/libjvm.so
#13 0x402fe2e2 in CMSCollector::collect_in_background(int) ()
   from /usr/j2se/jre/lib/i386/server/libjvm.so
#14 0x40309dfa in ConcurrentMarkSweepThread::run() ()
   from /usr/j2se/jre/lib/i386/server/libjvm.so
#15 0x4053cde8 in _start(Thread*) ()
   from /usr/j2se/jre/lib/i386/server/libjvm.so
#16 0x4002a020 in pthread_start_thread () from /lib/i686/libpthread.so.0

  xxxxx@xxxxx   2004-08- customer 
  xxxxx@xxxxx   10/7/04 00:13 GMT

N/A

under test and review for Mustang.