[ubuntu] Unresponsive Login

Hi,

I recently replaced the mac os on my macbook pro 2010 with Ubuntu 16.04.

Problem:
I login from the ubuntu login screen and into my desktop and then close my macbook and open it again after a few minutes.
Sometimes when I open it again and I see the login screen, I cannot enter my password.
Typing is not responsive and no characters show up as I type.
However the mouse can still move.

So far all I have had to shut down my macbook and restart when this happens.
Upon restarting the login works as I would expect: I can type in my password.

I would appreciate any suggestions on this problem.