windows 10 – Why, suddenly, will some laptop keys (e.g. F2, tab) not respond until held down?

I am using an HP 450 Probook G6. Until a couple of days ago the keyboard had worked perfectly since the machine was new approx 2 years ago.

Suddenly, the F2 and Tab keys have started failing to register intermittently – they seem to “go to sleep”. This means that e.g. Ctrl+Tab to change apps won’t work. I’ve found that pressing and holding the key for approx 2 seconds sometimes “wakes it up”. The key then works normally again, for a short period (usually 30-60 seconds). Then it will stop working again and I will need to repeat the process.

I have tried the following, without success:

  • Checking all keyboard settings including e.g. sticky keys.
  • Checking all language settings including ‘input mode’.
  • Updating the BIOS.
  • Updating the keyboard driver.
  • Reverting to a system restore point a few days before the problem first occurred.
  • Searching extensively online for other suggestions.
  • Stopping other applications and services to try to identify another process that might be interfering with key presses.

I am running Windows 10 Pro, Version 10.0.18363, with latest updates. I am not running any keyboard interceptor apps. I haven’t deliberately installed any new software in the last week. Nothing is obviously wrong with the keyboard (e.g. spillages etc) and when the keys are working, they work completely normally, so I’m sure this isn’t a physical problem.

Does anyone recognise these symptoms? Before I try radical workarounds like remapping keys, can anyone suggest anything I could try to diagnose or fix this?