Hi, I am having a strange problem with Time Machine. I have a MacBook with Leopard and have been using Time Machine to back up to an external 500gb drive every day since last November. All worked fine until yesterday when I got an warning message saying I hadn't backed up for 10 days (though I had backed up the previous day as usual). I thought that was odd but clicked 'back up now' anyway. When it was still backing up half an hour later I checked its progress, and it said it was transferring 42gb and was going to take 4 hours. Since the *total* amount of stuff currently on my MacBook (& Time Machine) is only about 68GB, I thought this was an error and cancelled. Then I restarted and went out. When I got back TM had finished backing up but the external drive now says it has 128gb on it up from about 72ish before . Why did it seem to be doing the initial back up all over again and where did all this extra data go? Is this a known problem and is it likely to happen again?