I experienced it when I run app that use netx with jdk6 (jrockit or oracle's).
I noticed that netx release was built with jdk 1.4, so I tried rebuilding with the same jdk I use (1.6) and there is no problem then. Some small modifications are needed, though nothing fancy (see patch attached).
It seems it happens still in version 0.5, seems to be duplicate of with http://sourceforge.net/p/jnlp/bugs/4/.
I experienced it when I run app that use netx with jdk6 (jrockit or oracle's).
I noticed that netx release was built with jdk 1.4, so I tried rebuilding with the same jdk I use (1.6) and there is no problem then. Some small modifications are needed, though nothing fancy (see patch attached).