If so, what happens if you type this:

nano /etc/security/console.perms

Back where I started from
 

OK, I'm back to a working keyboard - after using my rescue cd to change the value back from 3 to 5. I'll try to revert back to 3 and see what happens. Any idea why changing it to 3 could cause my keyboard not to function? By "not functioning", I mean I get prompted with a login, but nothing happens when I type.

Linux users are as dumb as computers are, they need to be told exactly what you did and the exact result of you doing it. We are very poor at intepreting "I can't type" at any other meaning than "I don't know how to press the keys on the keyboard." :p

How to get good answers with your questions about Linux

You aren't using some oddball keyboard or one with some broken connections then? Nothins shows up when you type?

If so, I would edit your needed files from the rescue environment, then, since the keyboard works from that.