AFAIK Mozilla was only disabling older versions ..
As far as I know, Mozilla was only disabling older versions of the Deployment Toolkit. But that was 2 years ago. It was done, in an attempt to block attacks which were occurring at the time.. IF it was disabled the user received a prompt notifying them there was a security issue. I'm unaware of Mozilla doing it without the same sort of warning. (Here is where it was being discussed at the time)
Do you know if Mozilla has (recently) started disabling it again? And if so, without the warning?
I'm aware of the of the plugin check. Since Harv only mentioned Java wasn't detected on his system, I didn't think to suggest checking the plugin. Maybe he should try it to see if it's the cause of his problem. .
I still have Java installed. I don't know if the same is recommended for all users, but I feel comfortable (and safe) with it installed.