Since yesterday, pressing any Ctrl, Shift, or Alt key on my laptop causes several of those modifier keys—including the keys on the opposite side—to register at once. This makes shortcuts such as Ctrl+Alt+Delete unusable. I removed the other USB devices, uninstalled and reinstalled the keyboard drivers, and tested with a separate USB keyboard. The external keyboard works normally, but I'm unsure whether that definitively points to a hardware fault in the built-in laptop keyboard. What else can I check?
2 Answers
Because a separate USB keyboard works correctly, the problem is very likely limited to the laptop’s built-in keyboard rather than Windows or the keyboard drivers. You can confirm by booting from a live operating system or the laptop’s firmware setup and testing the keys there. If the issue remains, it’s hardware-related.
The keyboard matrix may have a short, possibly from liquid getting underneath the keys. That can make several modifier keys appear pressed together. For a laptop, the usual fix is to have the keyboard inspected or replaced; an external keyboard can serve as a temporary workaround.
Since this is an integrated laptop keyboard, replacing it would mean servicing the laptop rather than simply buying another USB keyboard.