Strange Electrical Problem

The jeep has been cutting off while driving. It also happens while in park. When it cuts off, all electrical power dies - lights, radio, etc. The engine will not respond when the gas pedal is pressed. But, if it is put into neutral before the engine dies completely, the engine will rev fine. If the engine dies completely, I just pull off onto the side of the road and sooner or later the Jeep will start back up again. This problem doesn't seem to happen at any specific time, it happens while idling, driving, and at different speeds. This is for a 1995 xj sport 2wd 4.0. Any help would be greatly appreciated.
-Matt

My jeep did this for a couple of trips...i had put in my optima in such a way that the battery hold down bolt was grounding out to the positive terminal...D'OH!! I still haven't gotten that passenger's side window to roll down since then.

As you are losing power to accessories at the same time (radio, etc) my first guess would be a bad ignition switch. But you indicated that the lights go out also, and if by that you mean headlights, it cannot be the switch.
Perhaps then check the fuseable links to the battery for an intermittent connection or corrosion. Also battery cables / terminals for good contact.

could be a bad ground somewhere

again, check/clean/change ALL connections