I get a very strange font for my Apple ID Password
I'm using Yosemite on a mid-2010 27" iMac.
When I am asked for my Apple ID and Password, I now get a strange window filled with some font which probably cannot be displayed. It is four rows of square boxes filled with the letter A followed by a space and then two more rows with the same boxes filled with the letter A. Below that are three boxes in one row.
If I type my password in and then click on the bottom right clickable box, I get logged in successfully.
I installed the Yosemite font a few days ago. Is that causing this or is it something else?
I'd like to paste in a screen shot of what I'm seeing but this community does not allow it.
iMac, OS X Yosemite (10.10.3), 27"