I have a 1 TB external Iomega HD and once in awhile I can get it recognized by the computer. When I can get it recoginized it starts out apparently backing up the chosen files but always stops responding at some point. I have seen references to maybe the extenal HD being too big for my system, maybe it is over heating, maybe it is going to 'sleep'. The user guide is woefully lacking in information. I chatted with an Iomega tech and he said it had nothing to do with the HD but with the OS, of course. I am using Windows 7 Home Premium SP1, 4 GB RAM. I was able to do one backup when I first got external in December, but not a system image. I have about 111 GB on my C drive and the external is a 1TB so plenty of room. It is so frustrating not to be able to do the backup I need. I have been trying with the Microsoft backup and restore. Yesterday gave up on that and downloaded a 3rd party software, EaseUS. It is very simple to use but it even stopped backup after a while. What could be the problem?