Thank ou for your help. I used a usb keyboard and the same thing happened. I could not log in in safe mode, but I finally hit F12 and ran a complete diagnosis which took hours. It indicated that nothing was wrong, but the keyboard started working. The next day the keyboard stopped working again. I repeated the F12 login ran another complete diagnosis and received the same nothing was wrong diagnosis but the keyhboard started working again. So far it still works. I am not sure what happened. What do you think?