Plug it in and the machine slows to treacle, then the screen goes black. Unplug it and everything returns to normal. The drive powers up and is never recognised. What is happening is a conversation with no reply: the operating system asks the drive to identify itself, the drive fails to answer, and the machine sits there waiting for a timeout that keeps not arriving. That is why the whole computer stalls rather than just the drive. It is also why leaving it connected in the hope that it settles down is a poor idea. Every one of those cycles is the drive attempting to read and failing, and if the underlying fault is mechanical, each attempt costs a little more of what is recoverable. The right move is to take it off that computer entirely and read it on equipment built to expect no answer.
| Media | External hard drive that powers on but is never recognised, and which hangs the host computer and blanks its screen while connected. |
| Reported situation | External drive · turns on · not recognised · makes the computer run slowly · screen eventually goes black while it is connected · recovery sought. |
| Fault class | A drive failing to respond. It powers but cannot answer the host, so the machine waits, stalls and hangs. The data is normally largely present and is reached by reading the drive at its own level and imaging read-only in controlled passes. Leaving it connected is the risk. |
| Equipment used | Read through a hardware write-blocker on PC-3000 UDMA, well away from the computer it was hanging, with read behaviour and slow or weak regions mapped first · imaged read-only on DeepSpar in controlled passes, healthy areas captured at speed, slow regions revisited gently, unstable behaviour managed and the drive rested · filesystem rebuilt in R-Studio, contents validated and written to fresh media. |
The symptom looks like a computer problem and is not. When storage is attached, the operating system expects a reply within a certain time. A healthy drive answers immediately. A struggling one takes several seconds, then several more, and the driver stack blocks while it waits. Because storage sits underneath a great deal else, everything above it stalls — file dialogs freeze, the desktop stops repainting, and eventually the display gives up.
So the machine hanging is a symptom of the drive, and it tells you something useful: the drive has power and is trying. It is not dead. It is failing to complete reads, which narrows the field to weak or damaged surfaces, marginal heads, or firmware struggling to handle a growing defect list.
The reason to disconnect immediately is that the retry cycle is not free. If there is head or surface damage, every timeout is another sequence of attempts in a bad region. Worse, ordinary operating systems are stubborn — they will retry the same sector dozens of times before giving up, which is the exact opposite of what a failing drive needs.
Controlled-pass imaging inverts that behaviour. Read the healthy material first, quickly, while the drive is at its best. Come back for the difficult regions afterwards in short attempts, with rests in between and the heads watched for instability. What you read first is what you are most likely to keep, and a drive in this condition has a finite number of good hours left in it. That is the whole argument for taking it off the computer it is hanging.
It came off the host machine entirely and was read on PC-3000 UDMA through a hardware write-blocker, which expects a drive not to answer and does not sit waiting on it. Its behaviour was mapped before anything was copied: which regions responded normally, which were slow, and where it stalled. It was then imaged read-only on DeepSpar in controlled passes — the healthy majority captured first at full speed, the slow and weak areas revisited afterwards in short attempts with rests between them, and unstable behaviour managed rather than driven through. The filesystem was rebuilt in R-Studio from the completed image and the files opened and checked.
Read off the computer it had been hanging, imaged in controlled passes, and the data brought back onto fresh media. The assessment cost nothing and ended with one fixed written figure, VAT included before any work started. This one stayed within imaging and file system work, so it ran as logical work under no fix, no fee — nothing recoverable would have meant nothing to pay. Had the casing needed opening for head work, half the figure would have fallen due before that stage with the balance only on a result, and the owner would have been told which band applied before agreeing to anything.
Unplug it, and take the freezing as information rather than as an inconvenience. The machine is stalling because the drive is failing to answer, which means the drive is trying and failing to read. Do not leave it connected to see whether it settles, do not run chkdsk on it, and do not start a file copy and go to bed — an overnight copy against a failing drive spends its remaining working life retrying the worst regions on the disk. If you want to salvage anything yourself, copy the most important folders first rather than working alphabetically, and stop the moment it stalls. Better still, send it, and let it be imaged in the order a failing drive can actually sustain.
Each file below comes from a genuine enquiry taken from households and firms across Aberdeen, Aberdeenshire and the wider north-east, anonymised so nobody can be identified. Each one sets out how the fault was reasoned through, what was done about it, and which equipment did the work.
No warning means no long decline, and no long decline usually means the data is all still there behind whatever stopped the drive presenting itself
Appearing in Device Manager only proves something is plugged in — the clicking is the mechanism failing, and every retry costs data
Power cycling with warmth and no spin is a board fault or a seized motor — and twenty years in a drawer does not fade the recording on the platters
Assessment is free and takes 2 working days at most once it lands, the figure is fixed in writing, and logical work carries no fix no fee. Begin online, or lift the phone.