NetX Error

On Arch Linux, via OpenJDK JVM, I receive the following error:
"You are using a buggy version of NetX. Please either downgrade or upgrade it and try again, or try another JNLP client."
This error occurs upon clicking "Play" on my character, however Java lets me log in just fine. I understand Linux was probably not your intended development platform, but things programmed in Java should work cross-platform, which leads me to believe this error can occur on Windows as well.
"You are using a buggy version of NetX. Please either downgrade or upgrade it and try again, or try another JNLP client."
This error occurs upon clicking "Play" on my character, however Java lets me log in just fine. I understand Linux was probably not your intended development platform, but things programmed in Java should work cross-platform, which leads me to believe this error can occur on Windows as well.