See http://www.netbeans.org/issues/show_bug.cgi?id=152648 for exact steps ho to reproduce this:

-open project stored in
http://qa.netbeans.org/modules/debugger/promo-h/MemoryView.zip
-Toggle line breakpoint on line 25 of the file FixAndContinue.java
-Invoke Debug File action form context menu of file FixAndContinue.java in Projects view
-Invoke Step Into until debugger stops on line 26
-Insert line before line 30 with code System.out.println("Added line");
-Change method call on line 31 to afterFix();
-Invoke Apply Code Changes
-Invoke Step Into until end of application
when reaching line 30 an error message is thrown:
#
# An unexpected error has been detected by Java Runtime Environment:
#
# SIGSEGV (0xb) at pc=0x061c372a, pid=7714, tid=3084200848
#
# Java VM: Java HotSpot(TM) Client VM (11.0-b15 mixed mode linux-x86)
# Problematic frame:
# V [libjvm.so+0x1c372a]
#
# An error report file with more information is saved as:
# /home/tester/NetBeansProjects/MemoryView/hs_err_pid7714.log
#
# If you would like to submit a bug report, please visit:
# http://java.sun.com/webapps/bugreport/crash.jsp
#
Java Result: 134
BTW: it might be a hotspot issue, but I did not find the hotspot category in this mess.