http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6532373

this workaround works:
Submitted On 01-JUN-2007

I worked with jcristau and christoph4 via IRC on #debian-x, and we managed to
track down the problem with broken locking in Sun Java 1.5 and 1.6. It only
occurs if Java finds the Xinerama extension, at which point it does something
broken with locking and triggers the assertion. If Java never finds the
Xinerama extension, it doesn't trigger the assertion for broken locking.

The following workarounds address this problem:

For sun-java5-bin:
sed -i 's/XINERAMA/FAKEEXTN/g' /usr/lib/jvm/java-1.5.0-sun-1.5.0.11/jre/lib/i386/xawt/libmawt.so

For sun-java6-bin:
sed -i 's/XINERAMA/FAKEEXTN/g' /usr/lib/jvm/java-6-sun-1.6.0.00/jre/lib/i386/xawt/libmawt.so

The same fix (applied to the appropriate file) might work for other
proprietary JDKs.

- Josh Triplett