After a fresh install and both upgrade and dist-upgrade of Elementary OS Loki I try to lock and then unlock my laptop.

After the screen is locked, when trying to unlock, screen turns to black and doesn't show me the password prompt to unlock, only the mouse pointer. I hace to restart LightDM every time in order to get a session back.

I'm using a Gateway NV55C Laptop with an Intel HD 4000 graphics card.

Do you know what the problem is?

Do you know a fix for it?