1. Reboot, press the F8 key during startup and choose "Safe mode with command prompt" (choosing standard "Safe mode" will not work).
2. Once you obtain a command prompt, type regedit, navigate to the HKLM\SOFTWARE\Lenovo\TVTGINA branch and rename or delete the "Plugins" key (it was referring to ACGina.dll).
3. Then reboot - in my case, this solved the problem and allowed me to login normally.