This exact issue started happening to me a couple days ago. I didn't notice any apparent cause. When I click or press any key, the screen goes black for a second, then reloads with a system alert sound to the normal login screen. After a successful login, the screen flashes the "Switch to Greeter" screenshot that was attached to the original bug before successfully logging in.
__uname__ Kernel: Linux Kernel Release: 4.13.0-38-generic Kernel Version: #43~16.04.1-Ubuntu SMP Wed Mar 14 17:48:43 UTC 2018 Network Node Hostname: redgray Machine Hardware Name: x86_64 Processor: x86_64 Hardware Platform: x86_64 Operating System: GNU/Linux 16.04.4 LTS -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1733557 Title: Login screen showing Authentication Failure Switch to greeter... To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/unity/+bug/1733557/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
