the rear hubs on the Cranbrooks are notorious for problems. i've read about the spoke flanges cracking, and even seperating from the hub.
in my opinion, upgrading the whole wheel is the way to go, but don't go the "Huffy" way.
you can buy a new Weinmann alloy wheel with thicker, 12 gauge stainless spokes, and a shimano coaster brake hub for under $40 from Weinmann DH-39 Alloy HD Rear Wheel Coaster Brake 26" / 36H 12G SS Black/Black
i've had a few of these, and they're ten times the quality of the stock Huffy wheel.
(edit) i have about 1200 miles on a Shimano Hub, most of that at full throttle. besides regreasing it once or twice (just because i like to,) i've had no problems with it.