Be sure these drives are not USB powered. If they are you see thousands of complaints like this.
Fix? Pull the HDD out of that USB case and into a powered HDD case.
hey all, i am having wd 320gb and hitachi 500gb external drives. both of them r having same problem now. i dont know what happened to them, problem is that if i copy anything from any laptop or any pc it copied easily, last night i have copied more than 200gb data. if i copy any thing from hdd to any laptop and pc it gives error in the very start to try again that file can not be copied. i need all my data from these hdds, can anyone help me out?