lightdm freezes often after I entered my passwort. It hangs exactly saying "logging in...". It's no total system breakdown though.
I found out that there is already an existing bug report for that problem which affects a lot of people: https://bugs.launchpad.net/lightdm/+bug/986967
some people in Launchpad report that the problem may be caused by deactivating the login sound with Ubuntu Tweak. I've done that so it might be true.
There are 3 dupiclate question for this problem on askubuntu too: