A federal judge threatened to put the state's prison system into receivership after warning that a prison guard contract renegotiated by Gov. Arnold Schwarzenegger harms reform efforts in the nation's largest state correctional system. The California Correctional Peace Officers Association, the guard's union, already has a pattern of interfering with investigations and employee discipline, U.S. District Judge Thelton E. Henderson wrote Monday in a letter received Tuesday by Schwarzenegger. Schwarzenegger's proposal would worsen problems by granting even more concessions to the union in return for postponing pay increases, despite numerous warnings from a federal court special master, witnesses at Senate...