I was convinced that the user table wasn't being installed properly, and undid some of the changes that set the table prefix for that table--It turns out that this was really a session cookie issue on my machine, so I will restore that functionality to the installer.
Edit: 29-mar There is another bug that halts the new installer if a LUM_User table exists, even if you are installing to a different prefix. I'll check this in when that bug is fixed.