Hi. Recently I bought ADATA HD680 external HDD. I noticed, that sometimes it has slow transfer speeds - up to 15 MB/s. When this problem occurs, I need to disconnect drive from PC and then connect again. After reconnecting, speeds are great - up to 110-120 MB/s. As for now it happened only 3 or 4 times, but I don't know what causes this problem and if I need to return drive for repair.