Filter Keys is a potentially annoying Windows feature that ignores keyboard input unless the key is held down for a significant period of time. It’s also triggered when you hold down a button such as SHIFT for 8 seconds. The procedure for disabling (fix) Filter Keys varies between Windows versions.
Disable Filter Keys in Windows XP
Click Start → Control Panel → Accessibility Options.
Go to the Keyboard tab.
Un-check the box labeled “Use FilterKeys”.
Click the Settings button.
Un-check the box labeled “Use Shortcut”.
Press OK twice to save your changes.
Disable Filter Keys in Windows 10
The procedure to turn off Filter Keys in Windows 10 is very similar to the steps for XP — the difference being a few of the links and buttons contain a new language.
Click Start → Control Panel → Ease of Access Center.
Click “Make the keyboard easier to use”.
Un-check the box labeled “Turn on FilterKeys”.
Click “Set up FilterKeys”.
Un-check the box labeled “Turn on FilterKeys when right SHIFT is pressed for 8 seconds”.