I was doing Lyle McDonald's suggested weight program on 25-30 carbs/day, and had frequent bonks of the type you describe. It felt like suddenly my muscle strength would go and I absolutely could not do another rep...although I was fine on the rep immediately before the bonk. It was especially scary on the bench press, but fortunately the Gym Goddess smiled on me and I never had any accidents.

Just began "trial runs" of the BFL workouts and no bonking so far, but horrible muscle soreness instead. Was not prepared with glutamine...oops

Emily