This about the 8th HD that this has happened to. They are all between 160gig and 200gig and I have used Seagate, Western Digital and Maxtor Drives on different PC's and with Win98 and WinXP and I get the same problem on all of them. I use the drives as backup drives (I am using Second Copy to make backups) and I make backups every hour.The drives will work fine for about a month to 6weeks and everything will seem fine. Then one day I will shut them down and the next morning start them up and I will get a message that I need to format the drive because it is unrecognisable. Everything is then gone, if I click on properties it shows 0bytes on size and that the format is raw. All drives I always format NTFS. I am using a 34 PC peer-to-peer network with 5 Win98 PC, 2 Win2000 PC's and the rest XP.The PC storing the Drives is connected to a surge protector and it has only XP and Second Copy installed on it.