My keyboard has never had this problem in the past but lately I've been forced to use the on screen keyboard as mine will not work well at all to type in my password in the login screen. It is extremely laggy and won't even register some keystrokes even after a long period of waiting.
Once I log in however my keyboard works perfectly fine again so I don't know why this problem would occur only on the login screen and only on bootup (when I lock my computer and unlock it the keyboard once again works fine).
This problem just started happening so if anyone knows a fix the information would be appreciated.