Java web start doesnt work

Binary package hint: ia32-sun-java6-bin

Java web start (possibly other java apps too) doesnt work on latest hardy,

Locking assertion failure. Backtrace:
#0 /usr/lib/libxcb-xlib.so.0 [0xb7f8c767]
#1 /usr/lib/libxcb-xlib.so.0(xcb_xlib_unlock+0x31) [0xb7f8c8b1]
#2 /usr/lib/libX11.so.6(_XReply+0xfd) [0xb55762ed]
#3 /usr/lib/jvm/java-6-sun-1.6.0.03/jre/lib/i386/xawt/libmawt.so [0xb5a3964e]
#4 /usr/lib/jvm/java-6-sun-1.6.0.03/jre/lib/i386/xawt/libmawt.so [0xb5a17f97]
#5 /usr/lib/jvm/java-6-sun-1.6.0.03/jre/lib/i386/xawt/libmawt.so [0xb5a18248]
#6 /usr/lib/jvm/java-6-sun-1.6.0.03/jre/lib/i386/xawt/libmawt.so(Java_sun_awt_X11GraphicsEnvironment_initDisplay+0x2f) [0xb5a1854f]
#7 [0xb5d2a68e]
#8 [0xb5d22edd]
#9 [0xb5d22edd]
#10 [0xb5d20243]
#11 /usr/lib/jvm/java-6-sun-1.6.0.03/jre/lib/i386/client/libjvm.so [0x620bc6d]
#12 /usr/lib/jvm/java-6-sun-1.6.0.03/jre/lib/i386/client/libjvm.so [0x630a828]
#13 /usr/lib/jvm/java-6-sun-1.6.0.03/jre/lib/i386/client/libjvm.so [0x620bb00]
#14 /usr/lib/jvm/java-6-sun-1.6.0.03/jre/lib/i386/client/libjvm.so(JVM_DoPrivileged+0x34b) [0x62619bb]
#15 /usr/lib/jvm/java-6-sun-1.6.0.03/jre/lib/i386/libjava.so(Java_java_security_AccessController_doPrivileged__Ljava_security_PrivilegedAction_2+0x3d) [0xb7d3b96d]
#16 [0xb5d2a68e]
#17 [0xb5d22d77]
#18 [0xb5d20243]
#19 /usr/lib/jvm/java-6-sun-1.6.0.03/jre/lib/i386/client/libjvm.so [0x620bc6d]
java: xcb_xlib.c:82: xcb_xlib_unlock: Assertion `c->xlib.lock' failed.

Workaround: sudo sed -i 's/XINERAMA/FAKEEXTN/g' /usr/lib/jvm/java-6-sun/jre/lib/i386/xawt/libmawt.so

Dont know why.... but it works