Sounds like your keyboard may be acting up.
Try turning it off and connecting an external keyboard. Via USB port.
try the following...
1. Uninstall the keyboard driver.
2. Reboot the computer (without reinstalling the driver).
3. When it restarts, it should reinstall the driver on its own.
If you can type fine with the external keyboard, then there is something wrong with the attached keyboard and you need to have it looked at or possibly replaced. If, however, even the external keyboard does this then you could have a virus, malware, etc. on the laptop, or worse you could have a motherboard problem.