A Cruzer that worked for five years, sat unused for a long stretch, then failed the moment it was needed. Windows called the directory corrupted, and then the stick disconnected on its own — repeatedly, without being touched.
The client was about to reformat their laptop and reinstall Windows, and used the Cruzer to hold their work files while they did it. The files copied on without trouble.
Copying them back, Windows returned “the file or directory is corrupted and unreadable”, and shortly afterwards the stick disappeared from the system entirely, as though it had been pulled out. Reinserting it repeated the cycle: visible briefly, then gone.
Everything they needed was on it and nowhere else, and the laptop wipe was already scheduled.
A stick that disconnects itself is not a loose socket, and the distinction is worth drawing because it changes what you should do next.
The controller inside a USB drive is a small processor running firmware. When it meets flash it cannot read cleanly it retries — and modern controllers retry rather cleverly, re-reading the cells at shifted reference voltages to try to resolve a value that has drifted, then leaning on error correction to reconstruct what the raw read could not.
Where all of that fails, some controllers report an error, and some hang. A hung controller is caught by its own watchdog timer and reset.
To the computer, that reset is indistinguishable from the device being unplugged and plugged back in: the USB connection drops and re-enumerates a moment later. So repeated automatic ejection is a controller stuck in a loop, meeting the same unreadable region every time it retries.
Practically, that makes ordinary copying impossible. Every attempt gets a few seconds before the device vanishes and Windows abandons the transfer — and no amount of reinserting changes the outcome, because each cycle runs the identical sequence.
The stick worked perfectly for years and then sat unused. That detail is almost certainly the reason, and it is not widely understood.
Flash stores each bit as a quantity of electrical charge held on a gate, isolated by a thin insulating layer. That insulation is very good and it is not perfect. Charge leaks away over time, and the rate rises with three things: how many times the cell has been erased and rewritten, the temperature it is stored at, and simply how long it has been sitting.
As the charge drifts, the voltage separating one stored value from another narrows. The controller compensates — that is what read-retry at shifted thresholds is for — until the drift exceeds what error correction can resolve, at which point the cell no longer reads reliably.
Powering a device periodically lets the controller notice weak cells during normal reads and rewrite them at full charge. A stick in a drawer never gets that opportunity.
Which is the useful and unwelcome point: flash is not archival media. A USB stick or memory card put away as the long-term copy is being asked to do the one thing the technology is worst at. A hard disk in a drawer holds its magnetic state for decades; a flash device is quietly discharging the whole time.
The stick was reached at controller level rather than through the normal USB interface, which is what made the job possible: at that level the flash can be read without the controller’s error handling being able to reset the device mid-transfer.
Imaging ran in short windows, working around the regions that triggered the hang and returning to them separately — weak areas read repeatedly until successive attempts agreed, since a marginal cell will return different values on different reads and agreement is the only test of whether a value is real.
Nothing was written to the stick at any stage.
From the completed image the FAT structures were rebuilt. The directory entries were largely intact, which is why the material came back with its original names and folders rather than as carved fragments.
About 99%, returned on fresh media, and the laptop rebuild went ahead afterwards.
Two things to take from it. If a stick ejects itself repeatedly, stop reinserting it — it achieves nothing and every cycle is another opportunity for a confused controller to write something unhelpful to its own metadata.
And the wider mistake had nothing to do with the hardware: a single USB stick was the only copy of everything, at precisely the moment the source machine was being deliberately erased. The stick failing was bad luck. Having no second copy at that moment was a decision. USB sticks and cards are from £250 +VAT after a free 48-hour diagnostic.
Send the device over with a short account of what happened to it. The diagnostic costs nothing and commits you to nothing, and the figure that follows is fixed in writing before anything is opened.
Nothing can begin until the device is on the bench, which makes this the only step that needs anything from you. Pack it properly, put your details in with it, and send it over. What follows is a free diagnostic and a written figure, in that order.
Posting it? Use something tracked and insured — whatever is on the drive is worth considerably more than the postage. Bringing it in? Weekdays, 9am to 5:30pm, and it still wants packing as above for the journey.
Tell us what the device is, what it is doing, and anything already tried — an engineer will come back with a realistic view of the odds and a price band, before you commit to posting anything.
We’ll be in touch shortly. For anything urgent, call 0161 871 0788.
The controller crashing and restarting. When it hits flash it cannot read cleanly it can hang, and an internal watchdog resets the chip — which looks identical to the stick being unplugged and reinserted. Repeated ejection is that loop running over and over.
Usually not. That message means the file system structures cannot be read, not that your files have been erased. On a stick that is also disconnecting, both symptoms typically share one cause: flash the controller cannot read reliably.
Charge leakage. Flash holds data as electrical charge behind an insulating layer, and that charge drifts away slowly — faster in older, more worn or warm-stored cells. Powering a device occasionally lets the controller refresh weak cells; a stick in a drawer never gets that.
No, and it is worth being blunt about. Flash is not archival media. Sticks and cards are for moving data, not keeping it — anything you want in five years should be on at least two devices that get powered up from time to time.
No. Each cycle runs the controller into the same unreadable region, and repeated resets give it more opportunity to write something that makes matters worse. If a stick is ejecting itself, stop and leave it alone.
From £250 plus VAT for sticks and memory cards, fixed in writing after a free 48-hour diagnostic, with most jobs no fix, no fee.
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