JDK crash, not aware of any action in NetBeans that might have caused it.
Filed in bugzilla http://netbeans.org/bugzilla/show_bug.cgi?id=210958.

Crash log attached.

# A fatal error has been detected by the Java Runtime Environment:
#
# SIGSEGV (0xb) at pc=0x00007fff8cf34b00, pid=89989, tid=6279364608
#
# JRE version: 7.0_04-b19
# Java VM: Java HotSpot(TM) 64-Bit Server VM (23.0-b20 mixed mode bsd-amd64 compressed oops)
# Problematic frame:
# C [libsystem_c.dylib+0x60b00] tiny_free_list_add_ptr+0x72
#
# Failed to write core dump. Core dumps have been disabled. To enable core dumping, try "ulimit -c unlimited" before starting Java again
#