Hello, everyone! My laptop's HDD became non-responsive after I ran CHKDSK with /F command from Windows 8.1 OS that was installed on it. The system couldn't boot from the disk thereafter. It hang every time at start-up screen where manufacturer's logo was displayed. Not only couldn't the OS boot from the HDD but it also couldn't boot from the DVD although BIOS settings had been set appropriately to allow OS installation in this manner (and this startled me). At that point I decided to use a USB enclosure to connect the disk to another laptop. Now every time I connect the disk via USB, I can see it in the Windows Explorer under "Devices and drives" section. However, my system slows down considerably (Task Manager shows high disk usage) and I can see a progress bar (built-in into the background of the path field of the Windows Explorer window) moving fast at first and then slowing down at the end but not disappearing. Fortunately, I've been able to transfer the data. The part I consider to be the most interesting: when the disk is plugged-in via USB I neither can launch DISKPART nor management console's "Disk Management". DISKPART halts at copyright banner. Mangement console's "Disk Management" displays blank window instead of disks and status bar with "Connecting to Virtual Disk Service..." message. When the disk disconnects, everything works as it normally does: disk usage drops, DISKPART launches properly and Disk Management lists all the disks. Turning the original laptop on with no disk inside makes it possible to launch OS installation from DVD but as soon as the disk is plugged-in (USB), the cursor switches to "wait" status (can be moved around) with installation window hanging (buttons and links not clickable) until the disk is disconnected. When the disk is disconnected, all becomes normal: cursor is an arrow, "Refresh" link and other buttons work. I've tried to format the disk by right-clicking on it in the Windows Explorer. The "Quick Format" was set as default so I went with this option. What surprised me again was that formatting progress bar wasn't moving and completed in an instant a few minutes later when the formatting ended successfully. This procedure haven't changed the odd behavior of the disk but freed-up its space. Windows Explorer being the only means of interaction with the disk, one thing I can do is try to format it again but this time with "Quick Format" box unchecked and wait up to several hours with my fingers crossed (no progress bar). Another option is to ask for your advice. P.S. I've launched CHKDSK with the disk's volume as parameter but so far it looks like it's stuck showing "The type of the file system is NTFS" message for the last 15 minutes or so. I think it's the furthest CHKDSK is going to go.