Finally put Slick Willy up on an I59 Boost-Sustain motor.  Flown fist thin' in t' mornin' with no wind.  Weight on t' pad was 3lb 8oz.  Motor came up t' pressure smartly and t' rocket cleared t' rail smooth and straight.  Boost looked great until about 40 feet or so and then t' rocket leaned over at about a 20-25 degree angle and started a long slow arcin' profile for t' remainder o' t' 7+ second burn.  I lost sight o' it after burnout, but a couple o' folks claimed t' see t' drogue event.  I would imagine it was movin' pretty dang fast horizontally when t' drogue charge went off.  My buddy Coops grabbed t' tracker and jumped on his quad t' hunt it down.  He found it on t' west edge o' t' lakebed approximately 1.5 miles away.  Both t' booster and upper payload sections had sustained minor zippers.  T' upper section had seperated but t' main chute was still inside.  It looks like when t' drogue deployed t' suden jerk also seperated t' upper payload compartment pullin' t' main charge igniter with it.  I actually found t' main charge intact inside t' payload tube.  T' igniter had been jerked right out o' t' powder container.  Besides t' small zippers thar was no other damage t' t' rocket and it should be back in action soon.  Still nay sure why t' boost went offline, but I will definitely think it through and fly this motor again.