New federal guidelines say thousands of U.S. homes tainted by Chinese drywall won't be safe unless they are completely gutted.The Consumer Product Safety Commission released the guidelines Friday. They say electrical wiring, outlets, circuit breakers, fire alarm systems, carbon monoxide alarms, fire sprinklers, gas pipes and drywall must be removed.About 3,000 homeowners, mostly in Florida, Virginia, Mississippi, Alabama and Louisiana, have reported problems with the Chinese-made drywall. A large quantity of the drywall was imported during the housing boom and after a string of Gulf Coast hurricanes. It has been linked to corrosion of wiring, air conditioning units, computers, doorknobs...