Today I decided to 'enter time machine' and check that all was well to find that all previous (bar one) time machine backups had disappeared!!!! I've recently attempted to 'restore' a new hard drive to the last backup, made three days ago, this is the alternative to cloning. That didn't work, and the system wouldn't boot. So I cloned my 'old' HDD to the new one using super duper, which worked (although the new drive didn't have as much data as the old, maybe - 9gb or so??). In addition Time Machine now also says that my TM disk is not large enough to be used as a backup??! Does anyone know why/how this happens? Is it something to do with restore from a time machine back up? Any help would be greatly appreciated. MMT XT On a happier note, the new drive I purchased and put in, 500gb Momentus XT, has turned my MBP into a ridiculously fast machine, the time from turn on to the system becoming usable is literally 2/3's less. There is no discernable extra noise 7,200 rpm vs 5,400 rpm, and actually less noise as the drive has more room (less buzzing around) and perhaps the programmes I use the whole time are pretty much always the same so some of it is coming out of the flash memory (...maybe, maybe not). So all in all it appears to be working very well, and is recommended.