Platform: Linux (Ubuntu 10.04)
FAILS(CRASHES): JDK 7 (reproduced with b95, exact build where problem was introduced is unknown)
PASSES: JDK 6

The following code leads to JVM crash:
--------------------------------------
import java.awt.*;
import java.awt.font.*;
import java.awt.geom.*;


public class FontTest {
    public static void main(String[] args) {
        new Font("CustomFontName", java.awt.Font.BOLD, 12).getFamily();

        // the following will also lead to JVM crash
        new Font("CustomFontName", Font.BOLD, 12).createGlyphVector(new FontRenderContext(new AffineTransform(), false, false), "abcd");

        new TextLayout("012", new Font("Helvetica", Font.PLAIN, 12), new FontRenderContext(new AffineTransform(), true, true));

    }
}


------------------------------------------------------------------------
# To suppress the following error report, specify this argument
# after -XX: or in .hotspotrc: SuppressErrorAt=/jniHandles.hpp:189
#
# A fatal error has been detected by the Java Runtime Environment:
#
# Internal Error (/BUILD_AREA/jdk7/hotspot/src/share/vm/runtime/jniHandles.hpp:189), pid=1552, tid=3063851888
# assert(handle != NULL) failed: JNI handle should not be null
#
# JRE version: 7.0-b95
# Java VM: Java HotSpot(TM) Client VM (19.0-b01-fastdebug mixed mode linux-x86 )
# An error report file with more information is saved as:
# /home/sycob/dev/playground/hs_err_pid1552.log
#
# If you would like to submit a bug report, please visit:
# http://java.sun.com/webapps/bugreport/crash.jsp
#
Current thread is 3063851888
Dumping core ...
------------------------------------------------------------------------
Initally failure occured with Motif L&F
-Dswing.defaultlaf=com.sun.java.swing.plaf.motif.MotifLookAndFeel

And looked the following way

#
# A fatal error has been detected by the Java Runtime Environment:
#
# SIGSEGV (0xb) at pc=0x00dabc27, pid=17279, tid=74648464
#
# JRE version: 7.0-b90
# Java VM: Java HotSpot(TM) Client VM (18.0-b03 mixed mode linux-x86 )
# Problematic frame:
# V [libjvm.so+0x252c27]
#
# An error report file with more information is saved as:
# /net/jessika/export/jck/qa-results/jck/7/ea/b35/results/promoted/hs_err_pid17279.log
#
# If you would like to submit a bug report, please visit:
# http://java.sun.com/webapps/bugreport/crash.jsp
#


Was easily reproduced without Motif L&F on Ubuntu 10.04 within VirtualBox
bigapps/runThese/stability fails with same crash