Upgraded packages in Ubuntu Feisty in the past 24 hours have broken Java 6 (package sun-java6). Netbeans and other Java GUI applications no longer work. The error is as follows:

$ /opt/netbeans-5.5/bin/netbeans
java: xcb_xlib.c:50: xcb_xlib_unlock: Assertion `c->xlib.lock' failed.
Aborted (core dumped)


Bug #86103 has been filed at launchpad.net

It seems to be an issue with recently pushed out Feisty package updates for libX11 or mesa have the use xcb flag turned on. Downgrading the offending packages seems to be the best workaround at the moment.