Over the past week i have been having big problems with my Time Machine backup drive. My backup drive is an Iomega Helium 500GB partioned as HFS+ Journaled. I usually backup every two days so i plugged into my macbook pro on wednesday night. I left it for about 15 minutes and came back expecting the backup to be done. Instead I found it was deleting old backups? I thought this was odd as the drive had 150 or so GB free and i only had a few for songs and documents since my last backup on monday. After another 15 minutes i returned to find it was backing up 120GB!!!! I had no idea where it had come up with that insane amount of data. so i checked my mac's hard drive space to find i had 236GB free just like it has been around that for a few weeks. I let it back up and unplugged it later that night. I forgot to backup on friday so i plugged it in this morning. It was deleting old backups again and backing up a further 140GB!!! What the hell is going on??? I have now come to the conclusion that i should wipe the drive and start again. How can I do this?