I'm about off my head with frustration here. I know there are a lot of others who seem to have bumped into this particular problem but I haven't found any successful answer as yet. My desktop machine has a USB hard drive, 3.5 inch in a case, with a capacity if 1tb which I use as a storage medium of my video and music collections. This is seen as drive J and is working fine. I have recently bought another 2.5 inch laptop drive in a case for USB back-ups of stuff I can't afford to lose. I had a major disaster not so long ago and lost a complete hard drive so want to ensure a good back-up. Anyway, the drive is supposed to be plug and play and is sold as this sort of thing, ie a back-up drive. When I pop it into a USB port it shows as drive M which I've named it so that I can remember it easily, but when I point my cursor to it in My Computer it comes up as "There is no disc in Drive M. Insert a disc and click Continue" Drive M isn't in use by anything else. Well there's 650gb floating around there somewhere. When I try to populate the disc from choosing it in Device Manager, it shows 0MB. If I look at it from partitioning tools it shows as no drive capacity. Yet, when I pop it into my Laptop USB port it gives me the option of using it for storage, backups etc and allows full unimpeded use and in fact I have transferred quite large numbers of stuff over to it. I still can't access it from Win 7 on my desktop though. My laptop also uses win7 so I can't see where the problem lies. I have another hard drive installed in my desktop and that is exactly the same. The damn thing just doesn't show any size in it when selected. I feel slightly embarrassed now as I returned another back-up drive that showed the same problem as being faulty. PLEASE, what the hell is going on here and how can I mend it?