If the windows machine that jenkins is running on is restarted, or if the jenkins service is restarted, when it comes back up all my mac agents show as offline. If you look at the mac agents there is a java error showing up on them and you have to press the ok button and then relaunch the JNLP.

The error details on the mac are:
CouldNotLoadArgumentException[ Could not load file/URL specified: /var/tmp/javawsZAt0sJ]
at com.sun.javaws.Main.launchApp(Unknown Source)
at com.sun.javaws.Main.continueInSecureThread(Unknown Source)
at com.sun.javaws.Main.access$000(Unknown Source)
at com.sun.javaws.Main$1.run(Unknown Source)
at java.lang.Thread.run(Thread.java:744)