Newbie here and not much experience. have an emac with the G4 processor, 10.2.8 OS. trying to install 10.4 Tiger, plenty of space (31 GB) available but won't install. have run disk utility, repair disk and get "incorrect number of thread records" apparently there's some problem with the hard drive that disk utility can't handle. question: what/ if any after-market repair disk would you recommend?