I have a Seagate external hard drive that is 1.36 To and NTFS, that is connected to my laptop via a usb cable and that I haven't used so much since I bought it (about 2 years ago). I sometimes put video files that are large .mp4 and .avi files (more than 1 Go) on it. Almost every times I copy the video file on the external HD, the file become corrupted on it, the video is completely or partially unreadable from the external HD. The video can always be played without any problem from the hard drive of my laptop. So what I usually do is to copy the video file on the external hard drive, and try to read it from it to see if it's working. I almost always have to repeat this procedure 5 to 10 times before it actually works. What is going on?! I have 407 Go of data on my external hard drive, mostly my laptop ghost images and many video files. Do you think I have to format my external hard drive? I have an another external hard drive of about 1 To. I could possibly copy the 407 Go of data to the other external hard drive, do the format, and then copy back the data on my external hard drive. What would you suggest me to do? Thank you very much in advance!