Your mouse is double-clicking on its own
It starts small. A file opens twice. A dragged tab drops itself halfway across the screen. In a game, single fire becomes a stutter of two. You blame the driver, the game, yourself — because the mouse feels exactly the same as it always did.
The mouse feels the same because the failure is invisible to fingers. Under each button sits a micro-switch: a strip of springy metal that snaps against a contact when pressed. Rated for twenty, fifty, eighty million operations. As the spring fatigues, it stops snapping cleanly and starts chattering — bouncing against the contact for a few milliseconds before settling. Electronics inside the mouse are supposed to filter this ("debounce"), but the filter has a tolerance, the wear keeps growing, and one day the chatter pokes through as a second click.
Proving it beats describing it
Support threads about this go in circles because the evidence is anecdotal. Make it numeric instead. Open our double-click checker and click thirty times at your normal, calm pace. The tool times the gap between every pair of clicks. A deliberate human double-click has 80 ms or more between presses; nobody's finger produces an 11 ms gap. If your calm single clicks are throwing gaps under 30 ms — and doing it repeatedly — the switch is chattering. Two minutes, and you have a measured, repeatable fault instead of a feeling.
The warranty conversation
Mice from the big brands carry one- to three-year warranties, and phantom double-clicking is the single most replaced fault. The magic is specificity. Not "it double clicks sometimes", but: "single clicks are registering as doubles with gaps of 10–25 milliseconds, consistent with switch bounce." Attach a screenshot of the checker's verdict and gap log. That phrasing tells the support agent you've isolated the known failure mode, and it usually skips you past the reinstall-the-driver script entirely.
If you'd rather fix than ship
Out of warranty, two roads. The soldering road: replacement micro-switches cost a couple of dollars, and swapping one is a beginner-friendly job on most mice — dozens of teardown guides exist for popular models. The software road: some vendor utilities and OS tweaks add extra debounce time, which masks the chatter by ignoring fast clicks. It works, but it also eats legitimate rapid clicks — run the CPS test before and after and you'll see your butterfly ceiling drop. Masking has a price; the techniques piece explains why.
And if the checker says your switch is clean? Then believe it — test a different mouse, check the battery if it's wireless, and look at tap-to-click settings on trackpads. The tool has no stake in the verdict. That's rather the point.