I installed Ubuntu after it was released, and it worked well until I enabled a 2nd video card in my computer. Now, when I login, the font to show my name (in the click box, to select the user) is scrambled. I added 2 more users and their names are also scrambled. It looks like I need to reload the font associated with the user login. I tried to reload the system fonts (from a 16.04 discussion probably), but it did not make any difference.
How can I restore the text so it is legible, when I am initially logging into my computer?