Product Version: NetBeans IDE Dev (Build 20080318143646)
Java: 1.6.0_04; Java HotSpot(TM) Client VM 10.0-b19
System: Linux version 2.6.24-12-generic running on i386; UTF-8; en_US (nb)
Userdir: /space/netbeans/userdirs/nb-tr-1155

OS: Ubuntu 8.04 Hardy
-when the IDE starts then there is JDK message in console [5] "Locking assertion failure.  Backtrace:"

It can happen that the IDE won't start at all. The bug has been reported to JDK[1] and xorg[2] The issue should be
solved in new builds of JDK (Look at the [1] for more details).

The problem has been discussed at forums as well [3]

If you need a solution without updating JDK then follow [4]. Updating the Ubuntu with updates might help as well.

*[1]* http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6532373
*[2]* http://bugs.freedesktop.org/show_bug.cgi?id=11390
*[3]* http://forum.java.sun.com/thread.jspa?threadID=782829
*[4]* http://daveshuck.instantspot.com/blog/2008/01/29/cxliblock-failed-error-on-Java-applications
*[5]* Locking assertion failure.  Backtrace:
#0 /usr/lib/libxcb-xlib.so.0 [0xb5400767]
#1 /usr/lib/libxcb-xlib.so.0(xcb_xlib_lock+0x2e) [0xb540081e]
#2 /usr/lib/libX11.so.6 [0xb35cc518]
#3 /usr/lib/libX11.so.6(XGetVisualInfo+0x26) [0xb35c30a6]
#4 /usr/lib/jvm/java-6-sun-1.6.0.04/jre/lib/i386/xawt/libmawt.so [0xb36a4319]
#5 /usr/lib/jvm/java-6-sun-1.6.0.04/jre/lib/i386/xawt/libmawt.so [0xb36a4565]
#6 /usr/lib/jvm/java-6-sun-1.6.0.04/jre/lib/i386/xawt/libmawt.so [0xb36a53c9]
#7 /usr/lib/jvm/java-6-sun-1.6.0.04/jre/lib/i386/xawt/libmawt.so(Java_sun_awt_X11GraphicsEnvironment_initDisplay+0x2f
[0xb36a561f]
#8 [0xb5aebecd]
#9 [0xb5ae4edd]
#10 [0xb5ae4edd]
#11 [0xb5ae2249]
#12 /usr/lib/jvm/java-6-sun-1.6.0.04/jre/lib/i386/client/libjvm.so [0x621c40d]
#13 /usr/lib/jvm/java-6-sun-1.6.0.04/jre/lib/i386/client/libjvm.so [0x6310378]
#14 /usr/lib/jvm/java-6-sun-1.6.0.04/jre/lib/i386/client/libjvm.so [0x621c2a0]
#15 /usr/lib/jvm/java-6-sun-1.6.0.04/jre/lib/i386/client/libjvm.so(JVM_DoPrivileged+0x363) [0x6272153]
#16
/usr/lib/jvm/java-6-sun-1.6.0.04/jre/lib/i386/libjava.so(Java_java_security_AccessController_doPrivileged__Ljava_security_PrivilegedAction_2+0x3d)
[0xb7afd96d]
#17 [0xb5aebecd]
#18 [0xb5ae4d77]
#19 [0xb5ae2249]