Hello, I have a USB hard disk that I use to make backups of my system. Previously it has worked just fine. In fact it still does work fine on my work computer. Unfortunately, it is my home computer I am trying to backup, not my work computer. When I plug it it, it detects it fine. Then I try to mount the filesystem. The mount process hangs. Neither dmesg or /var/log/kern.log logs anything unusual. I can kill the mount process with ctrl-c, and the file system isn't mounted. I can then unplug the USB device if I so desire. Nothing is logged. However at this point the computer is "crashed", as if I type in "sync", the sync process hangs for ever too. If I wait long enough I get CPU x hung type messages. Shutdown won't work, I have to hard reboot the system. My working theory I have is that USB support on my motherboard may be dodgy. However this doesn't explain how the same drive has worked in the past, for the same computer, but suddenly doesn't work any more. Alternatively, maybe the entire motherboard is an unreliable piece of rubbish, and I should ditch it. Any ideas? This is running Ubuntu 12.04 64 bit. Thanks -- Brian May <brian@microcomaustralia.com.au>