I fixed this with the help of the TAC. The "cwpass" file was somehow corrupted. Repairing this file allowed me to login.
I'm suprised by two things. One, that a corrupt password file would not result in a "login denied" message. The behavior was that I was given a blank screen, not a denial.
The second suprise is that the file became corrupt. At time I noticed this problem, I hadn't touched the box in a few days.