In openSUSE 10.3, ImageJ with Java 1.6 can give an “Assertion `c→xlib.lock' failed.” error that prevents it running.

Open the file /etc/profile in your favourite text editor as the root user.

Then, add the the following statement just before the end of the file:

#  
# Enable lock assertion workaround
# 
export LIBXCB_ALLOW_SLOPPY_LOCK=true