My 1TB USB 3.0 was working fine earlier in Ubuntu as well as Windows. But lately it is not at all being detected in Ubuntu. It still works fine in Windows. I did update my Ubuntu to 12.10 but I am not sure if that caused the issue. When I connect my HDD and run dmesg | tail: [ 47.804676] usb 4-3: >Device not responding to set address. [ 48.008575] usb 4-3: >Device not responding to set address. [ 48.212421] usb 4-3: >device not accepting address 9, error -71 [ 48.324451] usb 4-3: >Device not responding to set address. [ 48.528340] usb 4-3: >Device not responding to set address. [ 48.732165] usb 4-3: >device not accepting address 10, error -71 [ 48.844138] usb 4-3: >Device not responding to set address. [ 49.048179] usb 4-3: >Device not responding to set address. [ 49.251881] usb 4-3: >device not accepting address 11, error -71 [ 49.251907] hub 4-0:1.0: >unable to enumerate USB device on port 3 The output of sudo fdisk -l is : Disk /dev/sda: 1000.2 GB, 1000204886016 bytes 255 heads, 63 sectors/track, 121601 cylinders, total 1953525168 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 4096 bytes I/O size (minimum/optimal): 4096 bytes / 4096 bytes Disk identifier: 0x00030cde Device Boot Start End Blocks Id System /dev/sda1 2048 1332981759 666489856 83 Linux /dev/sda2 1332981760 1953523711 310270976 5 Extended /dev/sda5 1332983808 1349365759 8190976 82 Linux swap / Solaris /dev/sda6 1349367808 1953523711 302077952 7 HPFS/NTFS/exFAT Disk /dev/sdb: 120.0 GB, 120034123776 bytes 255 heads, 63 sectors/track, 14593 cylinders, total 234441648 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x000a2519 Device Boot Start End Blocks Id System /dev/sdb1 * 2048 103368703 51683328 7 HPFS/NTFS/exFAT /dev/sdb2 103368704 154568703 25600000 83 Linux /dev/sdb3 154568704 234440703 39936000 7 HPFS/NTFS/exFAT /dev/sda and /dev/sdb are my 2 internal HDDs. But the external one which should be /dev/sdc is not even being shown though it is connected and the LED on the HDD is glowing. Someone had suggested adding blacklist uas to /etc/modprobe.d/blacklist.conf. Tried that as well. But still not working. Can someone help me out.