Thank you for any help!
We're getting this problem as well since JRE7_13 on Firefox 18.0.2. Same behaviour on Win7, WinXP and OSX. Interestingly, any example code continues to work so it must be something we are doing wrong, but it's worked as is for several years. OP any luck on fixing this?
I've filed a bug https://bugzilla.mozilla.org/show_bug.cgi?id=839967 but I'm having problems reproducing it in a testcase...everything works. Quite baffling, our application that had worked and still works with other browsers and with an old version of firefox (12) stopped working with the Java 7 update 13.