Some MBP keys won't work after logging in I have a 13 inch mid 2012 MBP, I'm having problems with some of my keys, some of my keys don't work such as u I O j k L m, but the wierd thing is that they work perfectly fine during the login screen, but don't work after logging in
Disable mouse keys which is an accessibility function.

Type ⌘⌥fnF5, and suppress the check mark there: