We study in this paper the problem of simultaneously scheduling resumable jobs and preventive maintenance on a single machine to minimize the earliness-tardiness cost. The machine is subject to random breakdowns according to Erlang distribution and minimal repair is considered. The age of the machine defines its probability of breakdown and performing preventive maintenance renews the age of the machine to zero, however the preventive maintenance operations cost valuable time that can increase the overall earliness-tardiness cost. A stochastic dynamic programming solving approach is presented for solving this problem with illustrated meaning to its algorithm.