You guys are running the wrong stuff if you are losing track bars on the trail. Aside from sloppy joint replacement, and bushing maintenance, a trackbar should never have an issue with coming apart.
Fraser your problem is obvious and that is you are running rubicon express, which like the rest of their crap they are notorious for having junk track bars.
Mud, I dont know what you are running, but if you put up some clear pics of your TB and the attachment points we can probably come up with some simple fixes that will permantly eliminate the chance of that happening again.