Sounds like you have some corrupt data somewhere. Have you tried pressing Int, Combi and Card whilst powering up?

This should reset the keyboard. Make sure you have back ups of anything you want on board as if I remember correctly, it wipes all the memory so everything appears with InitProgramme00 etc. (Long time since I owned an M1) You can then reload the factory originals.
This should at least tell you if you are running corrupt software or if something more sinister is ocurring.