Solution
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 an external keyboard works fine, then it could be the keys themselves that are the issue.

You may also want to try updating the Synaptics Driver if the above doesn't help.
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 an external keyboard works fine, then it could be the keys themselves that are the issue.

You may also want to try updating the Synaptics Driver if the above doesn't help.
 
Solution